Skip to main content

Full text of "Journal of the Society of Motion Picture Engineers"

See other formats

From the collection of the 


o PreTinger 





t P 

San Francisco, California 




Volume XXIX JULY, 1937 Number 1 



Progress in the Motion Picture Industry Report of the Prog- 
ress Committee 3 

Report of the Projection Practice Committee 39 

Report of the Committee on Exchange Practice 50 

Report of the Color Committee 54 

Report of the Non-Theatrical Equipment Committee 57 

Report of the Membership Committee 63 

Toning Positive Film by Machine Methods . . J. M. NICKOLAUS 65 

A Transmission-Measuring System Utilizing a Graphic Re- 
cording Meter W. W. LINDSAY, JR. 68 

Denham Studios of London Film Productsion, Ltd 


New Motion Picture Apparatus 

The Super Simplex Pedestal J. FRANK, JR. 94 

Current Literature 99 

Obituary Harry Pfannenstiehl 104 

Spring, 1937, Convention at Hollywood, Calif. 

Highlights of the Convention 106 

Final Program 1 10 

Society Announcements 116 





Board of Editors 
J. I. CRABTREE. Chairman 



Subscription to non-members, $8.00 per annum; to members, $5.00 per annum 
included in their annual membership dues; single copies, $1.00. A discount 
on subscriptions or single copies of 15 per cent is allowed to accredited agencies. 
Order from the Society of Motion Picture Engineers, Inc., 20th and Northampton 
Sts., Easton, Pa., or Hotel Pennsylvania, New York, N. Y. 
Published monthly at Easton, Pa., by the Society of Motion Picture Engineers. 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General and Editorial Office, Hotel Pennsylvania, New York, N. Y. 

West-Coast Office, Suite 226, Equitable Bldg., Hollywood, Calif. 
Entered as second class matter January 15, 1930, at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. Copyrighted, 1937, by the Society of 
Motion Picture Engineers, Inc. 

Papers appearing in this Journal may be reprinted, abstracted, or abridged 
provided credit is given to the Journal of the Society of Motion Picture Engineers 
and to the author, or authors, of the papers in question. Exact reference as to 
the volume, number, and page of the Journal must be given. The Society is 
not responsible for statements made by authors. 


President: S. K. WOLF, 250 W. 57th St., New York, N. Y. 
Past-President: H. G. TASKER, Universal City, Calif. 

Executive Vice-President, G. F. RACKETT, 823 N. Seward St., Hollywood, Calif. 
Engineering Vice-President: L. A. JONES, Kodak Park, Rochester, N. Y. 
Editorial Vice-President: J. I. CRABTREE, Kodak Park, Rochester, N. Y. 
Financial Vice-President: O. M. GLUNT, 463 West St., New York. N. Y. 
Convention Vice-President: W. C. KUNZMANN, Box 6087, Cleveland, Ohio. 
Secretary: J. FRANK. JR., 90 Gold St., New York, N. Y. 
Treasurer: L. W. DAVEE, 250 W. 57th St., New York. N. Y. 


M. C. BATSBL, Front and Market Sts., Camden, N. J. 

A. S. DICKINSON, 28 W. 44th St., New York, N. Y. 

G. FRIEDL, JR., 250 W. 57th St., New York, N. Y. 

A. N. GOLDSMITH, 444 Madison Ave., New York, N. Y. 

H. GRIFFIN, 90 Gold St., New York, N. Y. 

A. C. HARDY, Massachusetts Institute of Technology, Cambridge, Mass. 

K. F. MORGAN, 7046 Hollywood Blvd., Los Angeles, Calif. 

C. H. STONE, 205 W. Wacker Drive, Chicago, 111. 


Summary. This report of the Progress Committee covers the year 1936. The 
advances in the cinematographic art during that period are classified under the 
headings: (7) Cinematography, (IT) Sound Recording, (III) Sound and Picture 
Reproduction, (IV) Publications and New Books; (Appendix A) General field of 
progress of the motion picture industry in Great Britain, (Appendix B) Motion 
picture developments in Austria, (Appendix C) Report of the activities in the cine- 
matographic field in Germany during 1936. 

The Committee has been very successful in collecting material 
illustrating new advances in cinematography during 1936. Since it is 
practically impossible in a report of this nature to cover each and 
every advance in the art, many deserving items will undoubtedly be 
omitted. The greatest advances during the year seemed to take 
place in the field of sound recording and reproduction, the most 
interesting being the reproduction of push-pull recording and the 
use of ultraviolet light in both recording and printing operations. 
The year was noted by the introduction of a newer multicellular type 
of horn system for theater use, so that considerably improved quality 
of sound reproduction should be available to the public during 1937. 

The Committee this year is including a special appendix dealing 
with the motion picture industry in Germany, where considerable 
activity both in sound recording equipment and in substandard 
cinematography took place during the year. 

The Committee wishes to acknowledge the courtesy of the follow- 
ing firms for supplying materials and photographs for the report: 
Bell & Howell Company; Electrical Research Products, Inc.; Gen- 
eral Radio Company; International Projector Corp. ; Mole-Richard- 
son, Inc. ; RCA Manufacturing Corporation; Klangfilm, G. m. b. H. 


J. G. FRAYNE, Chairman 


* Presented at the Spring, 1937, Meeting at Hollywood, Calif. 



(.4) Professional 

(1) Films and emulsions 

(2) Cameras and accessories 

(3) Camera lenses 

(4) Stage illumination 

(5) Color 

(B) Substandard 

(1) Films 

(2) Cameras 

(3) Projectors 

(4) Color 

(5) Miscellaneous 


(1) General 

(2) Recording equipment 

(3) Accessories 


(1) Sound equipment 

(2) Projectors and accessories 


General field of progress of the motion picture industry in 
Great Britain. 


Motion picture developments in Austria. 

Report on the activities in the cinematographic field in Germany 
during 1936. 

(A) Professional (35 Mm.) 

The fact that there have been no startling innovations in pro- 
fessional motion picture photography need not detract from the fact 
that the steady forward movement indicates a healthy condition and 
a tendency to greater permanency in the art. The year 1936 saw no 
new or upsetting inventions or processes, but a general improve- 
ment in both materials and technic in the several phases of the allied 
cinematographic arts. 

(1) Films and Emulsions. During the past year numerous im- 
provements have been made in the Kodachrome process and, in 
addition, a new type has been announced. 1 The latter is intended 


for use with artificial light, and is compensated for the difference in 
color between incandescent lamps and daylight, for which latter 
source the original Kodachrome film was balanced. Filters have 
been provided for interchangeably using either film with either source. 
At the present time either type of emulsion is available in each of 
the amateur substandard widths, 8- and 16-mm., and, in addition, 
the film is available for miniature still cameras in the 35-mm. width. 

Announcement has been made by Agfa of a new color-film based 
upon the Fischer process. 2 Several emulsions coated upon the same 
support contain components in the separate emulsions that react 
with the developing solution to produce colored images. Following 
the development of the colored images the metallic silver is removed 
by a suitable bleach, thus increasing the transparency of the image. 

In the field of black-and-white films for the substandard cameras, 
a new high-speed panchromatic film has been made available. 3 

A new infrared-sensitive negative film for professional production 
work has been made available to the trade. 4 This type of material, 
in conjunction with red filters, is used principally for special effects 
such as night photography in full daylight. Since the film is insensi- 
tive to yellow-green, only a light red or orange filter is necessary to 
hold back the ultraviolet and blue for night effects. This not only 
speeds up the possible exposure, but also produces a much better 
balanced and more realistic picture. 

A radically new type of film for the production of duplicates from 
transparencies by a single step has been described in the JOURNAL.* 
This film takes advantage of the solarization property of emulsions. 
The reversal point in sensitivity is obtained not by overexposing the 
emulsion to light but results rather from a ripening process during 
manufacture in the presence of fog producing agents. 

A method for dry-hypersensitizing unexposed films and for treat- 
ing the latent image prior to development consists in exposing the 
sensitive material to mercury vapor. This method, as outlined pre- 
viously in the JOURNAL 6 consists in exposing the material to mercury 
vapor at room temperature and atmospheric pressure for a period of 
30 hours, if the film is not wrapped, or for six to eight days if the film 
is enclosed in the usual photographic black paper. 

The effect of humidity upon the sensitivity of photographic emul- 
sions has been studied by Charriou and Valette, 7 who reached the 
conclusion that exposure to excessive amounts of moisture reduced 
the emulsion sensitivity. Neither alcohol nor acetone was as effec- 


tive as water vapor in this respect. Rolleau reports a study of the 
effect of temperature upon sensitivity. 8 The results indicate that 
the sensitivity of an ordinary emulsion decreases with temperature 
in the range +20 to 60C. Orthochromatic and panchromatic 
emulsions were found to have sensitivity maximums at approxi- 
mately 20C., but this maximum disappeared when only blue light 
was used for exposing these materials. 

The development properties of peptized emulsions prepared with a 
minimum of gelatin with agar agar used to facilitate coating were 
studied by Steigmann. 9 Experiments by Marinesco 10 indicate that 
the blackening of photographic emulsions by supersonics is similar to 
that produced by light. 

An experimental factory for the manufacture of photographic 
materials was opened during the past year 11 in the U. S. S. R. The 
research workers in that country have reported a large number of 
observations on photographic phenomena in a series of papers. 12 
The subjects dealt with include the aging of emulsions ; the relation 
between the method of preparation of an emulsion and its resolv- 
ing power; the adsorption of sensitizing dyes by silver halides ; and 
other effects dealing with latent image phenomena. 

A systematic study of a group of cyanine sensitizing dyes has been 
reported by Hamer and Fisher, 13 while the properties of halogen- 
substituted cyanine dyes have been discussed in a separate paper. 14 
Additional progress in the preparation of new sensitizing dyes has 
been reported in a series of papers by Brooker. 16 A historical 
review of sensitizing dyes and their applications to photography has 
been given by Mees. 16 

(2) Cameras and Accessories. Though an unblimped silent 
camera failed to make an appearance, progress may be reported 
in that field. A number of studios equipped themselves with NC 
Mitchell cameras, to be used in conjunction with very light-weight 
blimps. Two major studios gave the latest Debrie Super-Parvo 
Cameras practical tests in actual production with favorable results. 
But perhaps the most outstanding camera so far developed has been 
made by the Twentieth Century-Fox studios, under the supervision 
of Grover Laube, as previously reported by the Committee. 17 It 
has made eight feature productions, and plans are now under way for 
the manufacture of several of them for use in the Fox studio. Aside 
from its being satisfactorily silent unblimped, it provides a greater 
shutter opening than is commonly used; has an improved optical 


system which speeds up its use ; the finder is not only more brilliant, 
but, due to its closeness to the shooting lens, parallax has been virtu- 
ally eliminated. Its movement, with a 200-degree shutter opening, 
and very fast acceleration and deceleration, permits the film to be 
perfectly at rest during exposure, increasing greatly the definition 
of the image. It is undoubtedly a big step forward in camera 

Columbia Studios developed a direct motor drive for high-speed 
camera work, remotely controlled by a rheostat, providing a smooth 
movement from 24 to 192 frames per second. This eliminates the 
gear-box with its attendant unsteadiness. This studio also de- 
veloped a variable diffusing device, or, rather, improved several 
existing devices, wherein the diffusion may be varied as needed, 
particularly in moving from a long shot to a close-up, where constant 
diffusion is undesirable. 

(3) Camera Lenses. Hal Mohr has reported a useful method of 
achieving greater depth of field in photography. 18 It consists in 
using a lens so mounted that it can be rotated about its nodal point, 
and setting the lens angle for each shot so that the near and far 
objects are in best focus on the film. The effect is exactly the same 
as if the camera were equipped with a swing-back. 

Several articles have appeared during the year that are of funda- 
mental interest to designers of optical equipment. Klughardt and 
Otto give measurements of the actual light transmission through 
photographic lenses 19 and show that the losses in modern high- 
aperture lenses are very great. Pritschow has analyzed the influence 
of optical and mechanical centering on high-speed anastigmats. 20 
An interesting article on the new organic glasses has also appeared. 21 

(4) Stage Illumination. For the period March 1, 1936, to March 
1, 1937, several new types of lamps have been made available. 
Perhaps most important is the No. 2 Photoflood introduced by the 
two Mazda Lamp companies as of July 1, 1936. This lamp has 
double the light output of the familiar No. 1 size. Its rated life is 
6 hours. Its greater light output makes it especially useful for 
amateur cinematography, particularly for color photography. 

The entire group of high-wattage studio lighting lamps such as 
the 5000-watt G-64 bulb; 10,000-watt G-96 bulb, and 2000-watt 
G-48 bulb have been made available at higher efficiency (temperature), 
and all lamps are designed for the same temperature, namely, 3380 
K, for color motion picture photography. These lamps are desig- 



nated CP, as contrasted with the designation MP for the regular 
motion picture types used for black-and-white photography. On 
account of the importance that all sources produce light of the same 
color for color work, the newer practice of designing for a fixed color 
of light has been adopted for the CP types. The Movieflood lamp 
made available several years ago is now a part of the CP group. 

Another new lamp designed especially for motion picture photog- 
raphy is the 1500-watt, 115-volt T-24 bulb, medium bipost type. 
This lamp is of the CP type intended for use in color work, and was 
developed especially for the new Mole-Richardson Inky scoop. 
The lamp has two rather unusual features: it represents the first 

FIG. 1. 

Flood Flash lamp and control equipment. 
(Courtesy General Electric Co.) 

use of the new medium bipost base smaller than the familiar Mogul 
bipost base now used on the 2000- and 5000-watt studio lamps, and 
it incorporates a wire mesh screen mounted above the filament, 
which absorbs the blackening that usually collects upon the bulb 
and greatly improves the maintenance of the initial light output of 
the lamp throughout life. The lamp is intended to burn base up. 

The past year has seen a considerable increase in the utiliza- 
tion of arc lamps as sources of photographic illumination. To meet 
this demand Mole-Richardson, Inc., have developed a new 65-ampere 
high-intensity arc (M-R Type 65), designed to meet the demand for 
a small, high-intensity arc spotlamp to match the characteristics 
of the Type 90, 120-ampere, and Type 170, 150-ampere, H-I arc 


spotlamps. This lamp has been designed so that its spectral char- 
acteristic in photography closely matches that of the higher powered 

The same company announces that the Solarspot style of lamps, 
which have proved so advantageous for motion picture photog- 
raphy, have been augmented by the addition of the M-R Type 206, 
500-watt, and the M-R Type 208, 1000-watt Solarspots. These 
lamps follow the general design incorporated in the 2000-watt Junior 
Solarspot and the 5000-watt Senior Solarspot, 17 and have been de- 
veloped to meet the demand for smaller lamps having a wide range 
of utilization. 

A new type of lamp of special interest to still picture photog- 
raphers is the new Flood Flash lamp announced by the General 
Electric Company, and shown in Fig. 1 with its control equipment. 
This is a 100- watt mercury lamp, mounted within a protective outer 
bulb. It can produce on the average of 30 lumens per watt, or as 
much light as the standard 200-watt filament lamp. This lamp may 
be flashed hundreds of times, the duration of the flashes being of the 
order of l /zo sec., permitting it to "stop" ordinary motion. 

(5) Color. In the color field, no doubt Technicolor, with their 
several pictures such as Ramona and Garden of Allah, showed the 
most pronounced improvement in the rendering of natural color and 
make-up. However, Cinecolor, Magnacolor, Cosmocolor, Dufay- 
color, Dunning, Keller-Dorian, and others came to the fore with 
strong claims. The quality of some of their work is such that it 
is safe to predict that a very strong color influence will be felt during 
the coming year. The projection of color backgrounds, and the 
painting of such backgrounds and the consequent matching of them 
photographically has been done very successfully, and will further 
the cause of color work immensely. 

The improvements in Kodachrome 1 and the impending introduc- 
tion of the new three-color process by Agfa 2 lends active interest to 
color photography and augurs well for the future of color in the 
cinematographic field. 

(B) Substandard Classification 

Progress in American substandard cinematography during 1936 
was confined mainly to improvement in existing equipment, film, 
and methods. There has been no outstanding change in the equip- 
ment designed. Manufacturers have concentrated their efforts to 


simplify and refine, apparatus. Sixteen-mm. projectors have been 
continually improved so that now the quality of both picture and 
sound compares favorably with that of 35-mm. equipment. In the 
meantime film manufacturers also have improved their products and 
have kept abreast of the increased demand for finer-grained films, 
made necessary by the increased size of screen images. 

These improvements are opening new fields to 16-mm. film, which 
is rapidly leaving the strictly amateur classification to enter the semi- 
professional field ; not as a competitor to 35-mm. film, but rather to 
augment it by filling the need of the smaller communities for film 
education and entertainment where the expense of 35-mm. equip- 
ment is prohibitive. Realizing this, one of the large film producers 
has, for the first time, announced the release of certain 35-mm. feature 
pictures on both 35- and 16-mm. film. 

The popularity of 8-mm. film is slowly increasing, being promoted 
by the development of well-built, satisfactory, low-priced cameras 
and projectors. Here, as in the 16-mm. field, the 8-mm. size is 
making amateur movies possible where the cost of the 16-mm. film 
and equipment is too great. 

Abroad, 1936 has witnessed the introduction of many new develop- 
ments in equipment and processes. Because of the several standards 
of width of film in popular use, European manufacturers of equip- 
ment have found it necessary to adapt their projectors to accom- 
modate various widths. In sound equipment flexibility was pro- 
vided in the claw movement to make possible the projection of 
sound-films produced according to the SMPE or the European 
standard. With the adoption of a single international standard 
(the SMPE) in 1936, it can be expected that this confusion will 
soon disappear. 

(1) Films. Hypan, a high-speed, fully panchromatic, fine-grain, 
non-halation, reversible film for outdoor use was produced by the 
Agfa Ansco Corporation. Kodachrome Type A, 1 for use with arti- 
ficial light, was introduced by the Eastman Kodak Company. 
Gevaert announced the introduction on the American market of an 
Ortho, a Panchro Super and a Panchro fine-grain reversal film. 
Processing stations were established in the United States for develop- 
ing the film. Gevaert double-8 reversible. film has also been made 
available on the American market. 

In England, Ilford announced the introduction of Selo fine-grain 
reversal film. The film has a tinted base, which, it is claimed, 



provides protection against halation and produces a more pleasing 
screen image during projection. Ilford also entered the field with 
a 9.5-mm., reversal, fine-grain film supplied in 30-ft. magazines. 

In Germany, Agfa has announced a new color-film for 35-mm. 
miniature and 16-mm. motion picture cameras. 2 

(2} Cameras. During 1936, the Eastman Kodak Company 
placed upon the market a magazine Cine-Kodak a 16-mm. motion 
picture camera which eliminates the difficulty of threading. The 
loading is so simple that it can 
be accomplished in three seconds. 
The entire range of Cine lenses is 
available to fit this camera, from 
the standard 1-inch lens to the 
6-inch telephoto. The camera 
may be operated at half speed, 
normal speed, or at 64 frames per 
second. Another Cine - Kodak 
was also announced during the 
year, the Model E, in the low- 
price range. In this camera, the 
supply and take-up spools are in 
the same plane, for simplifying 
threading. The camera is sup- 
plied with a fixed-focus, //3.5 

The Keystone Manufacturing 
Company introduced a new line 
of cameras of the 8-mm. type 
which will accommodate either 
ordinary 8-mm. or double 8-mm. 
film. The cameras are equipped with fixed-focus lenses and have 
adjustable speed. The Universal Camera Company of New York 
announced the Univex single 8-mm. camera, intended to be sold in 
the low-price field. Paillard-Bolex announced to the American 
market a new 16-mm. camera having many special features: speeds 
8, 16, 24, 32, and 64 frames; backward rewind for trick work; auto- 
matic threading; special view-finder to prevent parallax; audible 
footage indicator; visual focusing; and automatic footage indicator. 
The camera takes standard 100-ft. rolls of 16-mm. film. It has a 
turret lens mount and its weight is about six pounds. Zeiss-Ikon 

FIG. 2. Bell & Howell double-8 



abroad announced a new model 8-mm. camera known as Movikon 8. 
The camera is readily adjusted to take either single- or double-8 
film, the change-over being effected by the reversal of a single 
sprocket, which may be accomplished in a few seconds. The 
camera is equipped with a Zeiss //2 Sonnar lens. It has an optical 
range-finder and many other special features. Bell & Howell have 

FIG. 3. 

Model EE Kodascope. 
Eastman Kodak Co.) 


announced a new double 8-mm. camera using the Eastman type 
of double 8-mm. film (Fig. 2). 

(3) Projectors. A new Kodascope, Model E, and, more recently, 
a modification designated EE, was introduced. This Kodascope 
combines most of the desirable features of the Model L, such as 
interchangeable lamps up to 750 watts, and interchangeable lenses, 


including the 2-inch //1. 6. The performance of this Kodascope is 
thus on a par with that of the Model L, although its price is very 
much lower. It is shown in Fig. 3. 

Bell & Howell introduced a new 16-mm. sound projector known as 
the Model 138, intended for home and school use. It may be 
equipped with a 750- watt lamp and will accommodate 1600-ft. reels. 
Keystone developed a new series of 16-mm. projectors of die-cast 
construction. The projectors will accommodate a 750-watt lamp 
and may be equipped with an //1. 6 projection lens. Special features 
of the projectors are the forward or reverse projection and unusually 
silent operation. The Universal Camera Company of New York 
brought out an 8-mm. projector intended for the low-price field. 
Andre Debrie, Inc., of New York announced a new 16-mm. sound 
projector to meet the requirements of 16-mm. professional equipment. 
The machine embodies the features of high-powered illumination, 
extreme simplicity in threading, and a claw movement that is readily 
adaptable to either the SMPE or the former European sound-track 
standards. Ample cooling is provided so that the machine may run 
continuously without danger of overheating. Paillard-Bolex abroad 
announced a new projector accommodating 8-, 9.5-, and 16-mm. 
films. This new projector is said to have an unusually efficient light- 
source making large screen images possible with the smaller films. 
British Industrial Films announced a new 16-mm. sound projector 
built to take either the former European or the SMPE sound-track. 
The machine is strongly built for heavy-duty service, and is claimed 
to set a new standard of quality in type of sound reproduction. 

(4) Color. As has already been pointed out, a special Koda- 
chrome emulsion designed for use with artificial light was introduced 
during the year. This eliminated the use of a filter, and at the same 
time increased the effective speed about four times when used with 
artificial light. During the year, both the regular and the new Type 
A Kodachrome were made available in the 8-mm. size. The speed 
of regular Kodachrome was increased until it is now as fast as regular 
Panchromatic film. Processing stations for Kodachrome have been 
opened in London, Paris, and Australia, as well as in Chicago, Los 
Angeles, and Rochester. 

Although Pola-Screens have been available for some time, it was 
not until the past year that they were made available for Cine- 
Kodaks. Their use is highly desirable under certain conditions, 
such as for avoiding reflections from plate-glass windows, floors, etc. 



With Kodachrome, they are particularly valuable for rendering deep 
blue skies. This is the only way the blue color of the sky can be 
accentuated when using a color-film. 

(5) Miscellaneous. Two new lenses of wide usefulness were 
introduced for 16-mm. cine work: the 2 1 / 2 -inch//2.7 and the 4-inch 
f/2.7. A new optical view-finder for the Cine Special was introduced, 
which corrects for parallax. The Ampro Corporation has designed 
a special projector condenser lens of the duo convex type which is 
said to increase the light output considerably. Bell & Howell brought 
out a new automatic film splicer for single- and double-perforated 

FIG. 4. 

High-quality recording channel (Courtesy Electrical Research 
Products, Inc.). 

films, designed after models used successfully in the 35-mm. field. 
New lenses of various apertures and focal lengths for the Filmo 8 
and Double 8 were announced by the same company. The Pola- 
Screen was introduced by the Eastman Kodak Company. The 
RCA optical printer, announced late last year, has proved very' 
popular. 1936 has witnessed a substantial increase in the number 
in use and the amount of film recorded. 


(1) General. Progress in both recording and reproducing sound 
was very substantial during the year 1936. The use of class A 



push-pull recording mentioned in last year's report began to expand 
considerably during the past year. Universal Studio made a 
complete installation of push-pull recording and reproducing chan- 
nels, while experimental channels were put into operation at Colum- 
bia, General Service, and United Artists Studios. Squeeze-track 
recording, pioneered by the M-G-M Studios, was used very ef- 
fectively during the past year as a means of extending the volume 
range in such outstanding productions as The Great Ziegfeld, and 

FIG. 5. Portable recording machine. (Courtesy Elec- 
trical Research Products, Inc.) 

more recently in May time. Columbia also did some experimental 
work in this field during the past year. 

In reproducing, two-way horn systems, following the lead of the 
Fletcher two-way horn development, came into wide-spread use 
during 1936. Both Electrical Research Products, Inc., and RCA 
Manufacturing Company have offered these systems to the trade, 
while the Shearer horn system has had wide popularity. 22 The basic 
element of all these systems is the multicellular horn, credited origi- 
nally to E. C. Wente of the Bell Telephone Laboratories, described 
in last year's report. 


In order further to improve sound reproduction in the theater, a 
Committee of the Academy of Motion Picture Arts & Sciences has 
been actively investigating the optimal theater characteristic for 
sound systems. A report has been issued by the Committee and it 
is thought that general adherence to the recommended characteristic 
may prove generally beneficial to the industry. 

(2) Recording Equipment. During 1936 Electrical Research 
Products, Inc., completed the development of a high-quality portable 
recording channel (Fig. 4.). Two units forming parts of this channel, 
namely, the pick-up unit and main amplifier, were completed during 
1935 and reported by the Progress Committee last year. The com- 
plete channel is now in use by the industry and consists of the follow- 
ing principal components in addition to the two named above: 

FIG. 6. Four-ribbon light- valve. (Courtesy Electrical Research 
Products, Inc.) 

A portable noise-reduction unit of the carrier modulation type; a 
new recorder control unit, providing the usual recorder control 
facilities; and, in addition, an oscillator, light-valve overload bridge, 
and photocell amplifier output stage. The portable recording 
machine (Fig. 5) used with this channel has been designed primarily 
for quality recording, but has been made as light in weight as possible 
without penalizing its performance. In use, the channel is set up 
with the recording machine on top of the recorder control unit, with 
the noise-reduction unit at the side. This places all the operating 
controls within easy reach of the operator, and since the oscillator 
delivers sufficient power to modulate the light-valve 100 per cent, 
it is possible for the operator to set up and test the equipment during 
rehearsal without interfering with the mixer's monitoring circuit. 

During 1936 Electrical Research Products, Inc., developed and 
placed at the disposal of the industry experimental equipment for 



recording and reproducing push-pull sound records. A four-ribbon 
light-valve (Fig. 6) is used for recording all push-pull sound-tracks. 
This light-valve is of the clamped-bridge biplane type, and has proved 
quite rugged, holding its tuning and spacing for a long period of 
time. It can be used to produce either the push-pull or conventional 
type of sound recording. 

RCA announces that in the past year several of the major studios 
of Hollywood have been added to the list of licensees of the RCA 
Manufacturing Company. Commercial equipment for push-pull 

FIG. 7. RCA portable truck channel. 

recording with ultraviolet light was manufactured for installations 
at Hollywood, New York, and London. Many new custom-built 
trucks have also been provided with the new push-pull ultraviolet 
light recording equipment (Fig. 7). 

Demonstrations showing push-pull ultraviolet recordings printed 
with ultraviolet light on the RCA non-slip printer were made in 
Hollywood, New York, and London, and created a great deal of 
interest. It is claimed that the use of ultraviolet light 23 in making 
push-pull and standard variable-width recordings has increased the 
resolution of the sound-track, reduced fogging due to halation, and 



decreased the chromatic aberration of the lens system. This im- 
provement is very definite in listening tests, and quite pronounced 
when the sound-track is viewed under the microscope. The RCA 
non-slip printer 24 with ultraviolet printing appears to show consider- 
able improvement over existing printers. It is claimed that its 
design eliminates slippage between the negative and the raw stock, 
and provides automatic compensation for various values of film 
shrinkage. The use of this printer is free 
to RCA licensees, and several printer 
manufacturing companies have obtained 
licenses to manufacture and sell them. The 
new unidirectional microphone 28 (Fig. 8) 
was introduced this year, and a small 
number of units were made available to 
several motion picture studios for experi- 
mental use. Tests made so far indicate 
that this microphone has characteristics 
particularly useful for film recording. 

(5) Accessories. Electrical Research 
Products, Inc., has announced a peak read- 
ing volume indicator, which, as its name in- 
dicates, provides a ready means for visually 
determining the peak value of sound cur- 
rent. The indication of peak values of 
voltage is practically independent of wave- 
form, and the meter may be adjusted to 
have a slow restoring action for easy read- 
ing. The instrument provides a full indi- 
cation for sounds of very short duration. 

RCA has introduced a new neon volume 
indicator that makes it possible to monitor the volume level of 
the sound-track visually over a volume range of 48 decibels. It 
provides an accurate indication of peak voltage over the entire 
volume range; and control changing is eliminated. The unit is 
unique in operation, size, and design. 

The General Radio Co. has introduced the 759-A sound-level 
meter (Fig. 9), which, although developed primarily for making 
industrial noise measurements, has extensive application in various 
sound reproduction fields, particularly in measuring studio back- 
ground noise and the noise level in the projected sound record. 

FIG. 8 . Unidirec- 
tional microphone. 
(Courtesy RCA Manu- 
facturing Co.) 


The General Electric Company announce that the 10-volt, 7 1 /%- 
ampere, T-8 bulb lamp has been developed to a point where it does 
a fair job of recording by ultraviolet light. This has been done by 
the use of a bulb of ultraviolet-transmitting glass, and by using the 
horizontal filament coil. The advantage of winding the coil in an 
arc of about 5 /g to 3 /4-inch radius is twofold : closing up the turns on 
the concave side increases the quantity of the higher-temperature 
radiation emitted from the interior of the coil, and opening up the 

FIG. 9. Sound-level meter. (Courtesy General Radio Co.) 

turns on the convex side gives this higher-temperature radiation a 
better opportunity to escape from the interior of the coil, and also 
improves the uniformity of distribution of the radiation. 


Little notice has come to the Committee of new picture head pro- 
jectors in this country, although several new or improved sound 
attachments were introduced during the year. 

(1} Sound Equipment. Electrical Research Products, Inc., has 
brought out the Western Electric high-quality heavy-duty reproducer 
set coded T A -7400, forming part of the Mirrophonic sound system 



(Fig. 10). It has a sealed precision kinetic scanner to insure uni- 
form speed of film propulsion, and utilizes the latest type of projection 
optical scanning capable of accommodating single, push-pull, or 
double sound-track. In addition to these immediately applicable 
facilities, it has been designed with the thought in mind of its adapt- 
ability to probable future developments in sound recording. 

In the Western Electric diphonic speaker system (Fig. 11), Elec- 

FIG. 10. Western Electric high-quality reproducer. 

trical Research Products, Inc., has made available a speaker combina- 
tion that assures a quality of reproduction more natural and less 
machine-like than any previously attainable. The cellular con- 
struction of the high-frequency horn distributes the sound uniformly 
to all parts of the theater. The ample load-carrying capacity pro- 
vides a greatly increased dynamic range with the same natural 
quality throughout. 

RCA Manufacturing Company has introduced the type 1060 high- 
fidelity sound attachment (Fig. 12), which has a number of new 
features over previous designs. This unit may be used to reproduce 


FIG. 11. Western Electric diphonic loud speaker system. 


either push-pull or standard recordings. A unique and compact 
design of push-pull optics is employed, containing a prism assembly 
for bisecting the light-beam, so designed that all parts are readily 
accessible for cleaning and observation. A three-point rubber- 
suspended center-plate includes all the sound reproducing parts (i. e., 
rotary stabilizer and sound drum, pressure and lateral guide rollers, 
all optical parts, phototube and phototube transformer), which 
effectively isolates these critical parts from vibration. On the main 
casting are mounted all gears, driving sprockets, and the motor 
drive assembly. The motor is itself rubber mounted, and employs a 
universal coupling to the sound reproducer head. Another new 
feature is the inclusion of a flywheel on the motor shaft, which further 

FIG. 12. RCA type 1060 sound head (push-pull). 

insures uniformity of speed and allows the standard three-second start- 
ing time without reducing the starting torque, a particularly desirable 
feature in cold booths. The rotary stabilizer and sound drum shaft 
use newly designed ball-bearings with a grease seal to eliminate 
difficult oiling and keep out dirt. 

Further improvements have been made in the high-fidelity two- 
way loud speaker system employed by the RCA Manufacturing 
Company, to provide high efficiency, low distortion, and improved 
directional and distribution characteristics. Multicellular horns 
have been developed to provide a progressive series of sound-distri- 
bution angles to accommodate any type of. theater. 

The type PG-105 theater sound reproducing equipment has been 
marketed by the RCA Manufacturing Company for theaters up to a 
seating capacity of five hundred. This equipment employs the 


high-fidelity rotary stabilizer sound attachment, and a two-way 
high-frequency and low-frequency loud speaker system. Particu- 
larly interesting is the new amplifier (Fig. 13), designed with special 
consideration for accessibility and high-fidelity performance. The 
inclusion of the monitor loud speaker in the amplifier cabinet simpli- 
fies construction and increases accessibility. 

(2) Projectors and Accessories. The International Projector 
Corporation has announced the new Super Simplex pedestal. This 

FIG. 13. RCA type 1223 amplifier with 
monitor loud speaker, for small theater 

pedestal appears to meet all the requirements of modern projection 
and sound reproducing equipment, permitting a steadiness heretofore 
unequalled (Fig. 14). The same company has also introduced a 
slip-in gate for the Super Simplex projector that can be easily and 
quickly removed by unscrewing two thumb-screws. This permits 
the projectionist to clean it carefully at will. It also assures positive 
location of the guiding elements and is recognized as a device that 
meets a requirement of long standing. 

During the latter part of the year an intermittent sprocket that 
was hardened and accurately ground was introduced for use with the 




Simplex projector mechanism. The accuracy of the sprocket mate- 
rially assists in projecting a satisfactory picture, and the hardening 
process lengthens the life of the sprocket considerably. This sprocket 
is now being furnished on all new and repaired Super Simplex mecha- 
nisms and is unquestionably of the highest quality and accuracy of 
any sprocket in use. 

ERPI has introduced a new type of double-film attachment (Fig. 
15), designed as an adjunct to the new Western Electric heavy-duty 
reproducer. It provides a means of reproducing separate sound 
and picture records on 1000-ft. reels and permits the use of 2000-ft. 
reels when single film is run. The film in the double-film attachment 
is guided by means of idler rollers, or a driven sprocket as an alter- 
nate arrangement, and the film path is such that the sound-film enters 
the sound-head in essentially the same manner as it does for normal 
threading. There is no difference in the quality of sound obtained 
from film operating from the double-film attachment compared to 
that of film threaded in the standard manner. Strippers and idler 
rollers have been so located that film "jams" are virtually impossible. 


A number of valuable reports have been published during the past 
few years by the Academy of Motion Picture Arts and Sciences, 
Hollywood, Calif., and the British Kinematograph Society, London. 
The reports of the Deutsche Kinotechnische Gesellschaft appear in 
their official publication, Die Kinotechnik, and those of the Societe* 
Francaise de Photographie et de Cinematographic in the Bulletin of 
this society. In the U. S. S. R. the articles concerning motion picture 
progress appear in two journals, the Soviet Kino Photo Industry, and 
Photo Chemical Industry. 

A new motion picture publication made its initial appearance in 
January, 1936, known as the Journal of the Association of Cine- 
Technicians (London). 

Since the last report of the Committee in May, 1936, the books of 
noteworthy interest that have appeared are as follows: 

(1) International Motion Picture Almanac (1936-37); Quigley 
Publishing Co., New York, N. Y. 

(2) Year Book of Motion Pictures (1937), 18th Edition; Film 
Daily, New York, N. Y. 

(5) Kinematograph Year Book (1937); Kinematograph Pub- 
lications, Ltd., London. 


(4) Jahrbuch des Kino-Amateurs (Yearbook of the Cine-Ama- 
teur) (1937), edited by W. Frerk, Photokino Verlag., Berlin. 

(5) Abridged Scientific Publications from the Kodak Research 
Laboratories, Vol. 16, Eastman Kodak Co., Rochester, N. Y. 

(6) American Cinematographers Handbook and Reference Guide ; 
J. J. Rose, American Cinematographer, Hollywood, Calif. 

(7) Kino-Photo Scientific Research Institute, Vols. 1-3 (In 
Russian); Kinephotoisdat, Moscow. 

(8) International Dictionary of Cinematography (English, Ger- 
man, Italian, French); International Edition; E. Cauda, Editor. 
Stab, Tip "Leonardo da Vinci" Citta di Castello. 

(9) IX Congre"s International de Photographic Scientifique & 
Appliquee (Ninth International Congress of Scientific and Applied 
Photography), edited by L. P. Clerc; Revue d'Optique, Paris. 

(10} Motion Picture Laboratory Practice; Eastman Kodak Co., 
Rochester, N. Y. 

(11) Color Cinematography; A. Klein, American Photographic 
Publishing Co., Boston, Mass. 

(12) Natural Color Processes; C. E. Dunn, American Photographic 
Publishing Co., Boston, Mass. 

(13) II Cinematografo al Servizio della Scienza (Cinematography 
in the Service of Science) ; Quadrante, Rome. 

(14) Trick Effects with the Cine Camera; H. A. V. Bulleid, Link 
House Publications, Ltd., London. 

(15) Cine Titling Simplified; H. B. Abbott, Link House Publica- 
tions, Ltd., London. 

(16) Photography; C. E. K. Mees, G. Bell & Sons, London; also 
MacMillan Co., New York. 

(17) Photography To-Day; D. A. Spencer, Oxford University 
Press, London. 

(18) Filmentwurf, Filmregje, Filmschmitt (Amateur Films, Plan- 
ning, Directing and Cutting); A. Strasser, 2nd Edit., W. Knapp, 

(19) Filmtricke und Trickfilme (Filmtricks and Trickfilms); 
A. Stuler, W. Knapp, Halle. 

(20) Exposing Cine Films; D. C. Smethurst, Link House Publica- 
tions, Ltd., London. 

(21) Filmen mit Kodak 8 (Filming with the Kodak 8) ; A. Stuler, 
W. Knapp, Halle. 




Since 1927, when the Cinematograph Films Act was passed, 
British motion picture production has shown tremendously acceler- 
ated growth. The increase in production has naturally been accom- 
panied by improved facilities for making pictures, and enormous 
sums of money have been spent in building new studios, making 
additions to existing studios, and equipping them with the necessary 
technical equipment. The year 1936 was an eventful one in the 
annals of British production and it is hoped that a brief description 
of certain of the new studios, laboratories, and additions to existing 
studios, built during that year will be of interest to the reader. 

New Studios. May, 1936, saw the official opening of the London 
Film Studios at Denham, Bucks., a completely self-contained pro- 
ductipn center. There are seven separate stages, the four largest 
stages being air-conditioned. These buildings are of reinforced 
concrete construction, and the inside walls are covered with rock- 
wool for sound absorption. The sound system used is Western 
Electric. Complete protection from the weather is afforded by cor- 
ridors which connect the stages with the administrative block and 
the dressing room block. In the administration block are located 
two theaters, one of which is large enough to seat comfortably three 
hundred persons. The studio has one of the largest power plants in 
the country, having an output of 4400 kilowatts. 

Pinewood Studios at Iver Heath, Buckinghamshire, was officially 
opened on September 30, 1936. The studios are designed on the 
unit principle, each consisting of eight stages. It is understood that 
two units will be built, making a total of sixteen stages, but on the 
opening date only five stages of the first unit had been completed. 
Constructed on a steel framework, with solid concrete walls eleven 
inches thick, these stages show careful consideration necessary to the 
various requirements of production. Internally, the walls and ceil- 
ings are sound-proofed with slagwool. All approaches to the stages 
are under cover, an obvious necessity when one considers the inclem- 
ent weather prevalent in this country, and covered ways are also 
provided between the workshops and stages. Further, a covered 
space of about 15,000 sq. ft. in area is located in the center of the 
unit. For sound recording the Western Electric variable-density 
system is used. 


Additions to Existing Studios. During 1936 several English studios 
engaged in extensive additions to their premises. With the additions 
completed during the year Sound City Studios, Shepperton, Middle- 
sex, now has seven sound stages, totalling 80,000 sq. ft. of floor space. 
Built on the unit system, each stage has its own dressing rooms, 
production offices, property rooms, and many of the necessary acces- 
sory departments. In a separate block are contained twenty cutting 
rooms and three theaters. Standard sound equipment for these 
studios are the RCA ultraviolet and the Visatone sound systems. 
The Warner Bros.-First National Studios at Teddington, Middlesex, 
made extensive additions and alterations during the past year. 
The old studio, which has been in use for five years, has been modern- 
ized, and an entirely new sound stage has been built. 

Studios in Course of Erection. At the end of 1936 there were about 
twenty-five studios, totalling in all more than seventy stages, avail- 
able for production in this country, all situated in or near the London 
area. Some of these studios possess excellent technical facilities, 
and although others are not so completely equipped, it would cer- 
tainly seem that the number of studios is more than ample for the 
present requirements of British production. 

New Laboratories. Under construction during 1936, the new 
Technicolor Laboratories at Harmondsworth will fill the require- 
ments of those British producers wishing to make films in Technicolor, 
and will also, presumably, print color releases from American nega- 
tives. The buildings are brick faced, with long windows stretching 
the whole length of the frontage on both floors. Of special impor- 
tance to the Technicolor process, every room in which film is handled 
is completely air-conditioned, special care having been given to the 
control of temperature and humidity. Having a potential output 
of about 36,000,000 feet per year of finished prints, the new Techni- 
color Laboratory will take an increasingly active part in British 
productions. Also under construction during 1936 were the Denham 
Laboratories, situated close to the London Film Studios. The 
building is completely air-conditioned, and for that reason double 
glazed casement windows are used throughout. The windows in 
the cutting rooms are glazed with Thermolux, which effectively 
prevents light or heat rays from focusing upon material exposed in 
the room. Including these two new laboratories there are now 
twenty-one motion picture film processing laboratories in this coun- 
try, all situated in or near London. 



Technical Advances. The Western Electric Company has de- 
veloped a portable 16-mm. sound-film reproducing system primarily 
for road show service, and embodying a number of novel features 
(Fig. 16). The projector employs a single 450-watt lamp, which is 
used for the dual purpose of picture projection and sound scanning. 
The main drive is a synchronous motor, and a series motor having a 
saturated field constitutes the take-up mechanism. To compensate 

FIG. 16. Western Electric, Ltd. (London), IG-mm. sound- 
film projector. 

for the high-frequency loss inherent in 16-mm. film, variable high- 
frequency equalization is provided. Similarly an adjustable high- 
pass filter is provided to reduce the base effect in reverberant halls. 
Messrs. A. Vinten, Ltd., have a light gyroscopic tripod for light type 
35-mm. professional cameras and for serious work in 16-mm. The 
head is so constructed as totally to enclose the whole mechanism, and 
the oiling is such that it does not need renewing for at least five 
years. The head can be immediately removed from the bowl type 



spider and placed in a similar one of metal construction which can 
be readily fixed to an aeroplane wing or a carriage window. Another 

product for the year is an 
optical printer for producing 
double-8 amateur films from 
16-mm. (Fig. 17). 

Exhibition. The year has in 
all been an improved one for the 
exhibitor, although there is some 
concern over increased competi- 
tion due to the number of new 
cinemas. The consensus is 
that the extensive building pro- 
gram will ultimately be to the 
benefit of the exhibiting side, 
because obsolete redundant 
cinemas will be eliminated. 

The mutually advantageous 
association between the motion 
picture industry and broadcast- 
ing has continued. Commenc- 
ing in November, regular tele- 
vision programs have been 
radiated by the British Broad- 
casting Corporation, and the 
British Movietonews and Gau- 
mont British News are televised 
daily. At present, television is for home entertainment only in 
London and environs, and is not yet a source of competition to the 



The Austrian film industry operates under great handicaps. The 
fact that there are only six million German-speaking inhabitants in 
Austria reduces the profits of the film industry, especially when the 
sales are limited to Austria. The sales field in Germany is of no 

FIG. 17. Sixteen-mm. to double-8 
reduction printer. (Courtesy W. 
Vinten, Ltd., London) 

* Technische Hochschule, Institut fur Technische und wissenschaftliche Kine- 
matographie, Vienna. 


great advantage, since only a very limited film import to that country 
is permitted in return for export of an equal amount of photographic 
material into Austria. Furthermore, Germany does not permit 
payment of the imported goods in currency. Although the Austrian 
film industry is technically and artistically well equipped to produce 
large quantities of film, it can not avail itself of this opportunity 
because of barriers set up by other countries. 

The development of the photographic apparatus industry is cur- 
tailed for the same reasons, although excellent facilities, installa- 
tions, and ideas are available. 

In recent years several pieces of photographic equipment have 
been developed. The Ludwig Hauner Co. of Vienna produces 
a camera whose outstanding feature is a trick-shutter. The adjust- 
able sector of this device must be entirely open at the beginning of 
the change-over, otherwise the sector will not be closed in the as- 
signed number of turns of the crank. A shutter in which the change- 
over can be started from different opening angles of the sector is 
constructed by Ludwig Castagna Co. 

Motion picture projectors are built by Friedl and Chaloupka, 
Vienna. The framing is of special interest and is accomplished by 
turning the Maltese cross about its axis. This form of construction 
is unique and rather difficult, since the moving period must be kept 
in constant step with the position of the revolving shutter. The 
shutter is controlled directly by the driving mechanism, not depend- 
ing upon the Maltese cross, while the Maltese cross is adjusted by 
means of a differential gear to keep the moving period constant. 
The shutter, of the metal barrel type, is arranged between light- 
source and film. The safety shutter consists of a centrifugal 
shutter within a barrel shutter. The double-hinged gate is of 
interest. The gate hinge is close to the film- track in most pro- 
jectors, so that loading the film and cleaning the film-track are diffi- 
cult. The film is completely exposed upon opening the double- 
hinged gate, and the difficulties mentioned are entirely eliminated. 

The motor is mounted laterally and parallel to the base. An inter- 
mittent mechanism between motor and projector permits frequencies 
of 24, 25 l /t, and 27 frames per second. 

The cylindrical lamp housing is lined with highly polished alumi- 
num to prevent heat radiation. 

Substandard film cameras and projectors are manufactured by 






Cell iris 
Grid screen 

Parallel resistance 

FIG. 18. Automatic camera 


two firms. The automatic adjustment of the lens aperture of 
a camera made by Eumig is of special interest. A selenium cell 

with an adjustable shutter 
coupled to the diaphragm is 
placed next to the lens. The 
operation of the mechanism is 
illustrated in Fig. 18. At a 
certain aperture of the lens or 
of the photoelectric cell corre- 
sponding to a certain exterior 
brightness, the galvanometer 
indicator points to zero, as can 
be seen in the finder. If the 
exterior brightness changes, the 
indicator must be readjusted to 
zero by turning the cell dia- 
phragm. This changes the lens 
aperture correspondingly. The 
zero mark can be adjusted ac- 
cording to the sensitivity of the emulsion used. If the camera is 
not to be used for the standard number of exposures, namely, 16, 
the corresponding change of the lens diaphragm occurs auto- 
matically with the setting to the new speed. 

A color-film process upon which the inventors Gschopf and Pokorny 
have worked for years, nears completion and will be described in 
the near future. It is the "Irix" process, which is similar to the 
Technicolor process, but appears to have certain advantages over the 

Pure dyes in a colloidal solution are used for dyeing the printing 
matrix, instead of the usual hydrochlorides, acetates, sulfates, and 
other salts. The inventors recognized that the gelatin of the ma- 
trix as an amphoteric colloid absorbs the pure dye base very rapidly 
as a unilaterally electrically oriented substance and sufficiently retains 
it without chemical union, yet transfers it very rapidly and com- 
pletely to the image carrier containing precipitants for basic dyes, 
while even the slightest acid action causes rapid and complete bleed- 
ing of the dye base from the matrix. 

The absorption of these pure dye bases by the gelatin of the matrix 
and the transfer from the latter to the image carrier takes place 
within a few seconds. After the printing is completed, the matrix 


does not retain the slightest trace of the dye, and cleaning is un- 
necessary. The three color-separations are superimposed and the 
resulting image is grainless, sharp, light-proof, and water-proof, 
and not affected by most acids. In this lies the superiority of this 
process over other imbibition processes. 

The very simple exposure represents another advance of the in- 
ventors' tripack. Entirely new methods have been used in its 
making and in the emulsion technic in connection with sensitizing 
dyes and antihalation coloring. The result is a material of very 
high sensitivity, exposure range, excellent color separation, and 
extreme sharpness. It is sufficient to point out that the upper 
two emulsions of the tripack are almost perfectly transparent. This 
process is far superior to the process using several emulsions on ac- 
count of its wide exposure range and the extensive color correction 



The year 1936 showed notable progress in the cinematographic 
field, indicating clearly that whereas the 35-mm. film is intended 
exclusively for the theater, the 16-mm. substandard film is going to 
take its place more and more as far as schools, associations, and other 
official arrangements are concerned, and in which the audience is 
smaller than in the theaters. Also the business in the amateur 
field showed a great advance in Germany in that the 8-mm. sub- 
standard film is actually replacing the 16-mm. size. Consequently, 
during the year a considerable quantity of new apparatus came 
upon the market, covering the whole cinematographic field, and 
it would be difficult to give all details in this short report. 

The leading firm in the 35-mm. field, Klangfilm, brought out a new 
sound-film recording camera under the name of Eurocord, about 
which Klangfilm themselves write as follows: 

"It was the aim of the development to produce an apparatus that 
would comply, not only with regard to sound quality but also with 
regard to operating characteristics, with the highly advanced require- 
ments and would take into account the experiences of the last eight 
sound-film years. Due to extensive tests the double variable-width 
method was chosen for sound-film recording because it is superior to 
other recording methods by virtue of the length of the straight-line 
portion of the characteristic curve, and allows simple control of 


the treatment in the photochemical process. The reduction of noise 
is achieved by shading off the white parts of the sound area by means 
of an additional diaphragm 

"The recording device consists of an oscillograph having a dynamic 
driving mechanism, the noise of which is suppressed by oil, the change 
in the noise suppression due to changes of temperature being auto- 
matically compensated. The control of the sound volume is effected 
by optical pick-up and by a new sound volume indicator. This 
indicator consists of two instruments, namely, one indicator for the 
mean value and another for the peak value, both being arranged in a 
casing the size of a normal measuring instrument so that both can be 
read at one glance. The indicator for the mean value shows the 
mean volume of sound, while the indicator for the peak value also 
reacts on short impulses. 

"The apparatus is available in two types, one for connection directly 
to the main for work in the studio and the other one as a battery 
apparatus for outdoor exposures. Four so-called room microphones 
are used, two directional and two undirectional. The mixing table 
is movable so that it can also be brought to the scene. The sound 
camera is suitable for inner cassettes. The exposure is controlled 
photoelectrically . ' ' 

Since, however, not only good sound recording apparatus is 
required, but because there is also great interest in recording sound 
for other purposes in a more economical manner, Klangfilm has 
brought upon the market an apparatus about which they report as 
follows : 

"The broadcasting companies and certain scientific institutes 
have suggested the development of a sound recording apparatus that 
would allow high-quality recording and as long a reproduction as 
possible, so that subsequent corrections, cuts, and splices could be 
made. The apparatus should be easily movable and resist vibrations. 
Such equipment is especially needed for the analysis of non-recurring 
sounds which can not be done on the spot with sufficient accuracy. 
Recording on normal 35-mm. film is uneconomical, and for that reason 
Klangfilm is placing upon the market, at the beginning of 1937, new 
apparatus, so-called "Schmallfilmgerate," intended for unperf orated 
sound-film 1 / 6 of the normal film width (5.83mm.). The recording 
and projection are carried out at the speed of the standard film." 

In the same field Arnold & Richter, G. m. b. H., announce a new 
hand-camera for 35-mm. standard film containing double cassettes 


for 60 meters of film, which can easily be exchanged because the 
supply reel as well as the take-up reel are included in the cassette 
so that all threading is eliminated. The camera has a revolving 
head for three lenses (//2.3, focal length 28-75 mm.). The most 
important novelty of this new ARRI-Camera is the mirror-reflex 
arrangement, which allows a clear, upright, and parallax-free image 
of the picture during the running of the film. The motor for 
driving the camera is arranged vertically below the camera, and 
acts at the same time as a handle and stabilizer. 

The Standard 7 Aero Projector of Eugen Bauer G. m. b. H. was fur- 
ther improved last year, and a special characteristic is the flanged 
motor provided with a fan for supplying the film-gate and the film 
with cool air. This air impinges upon the film from four nozzles 
through channels in the ground plate of the film-track. 

As a further safety device, the air valves are controlled by the 
air blast. This safety device, called the Flammex, switches off the 
light-beam as soon as the film or a splice breaks, in the gate. In 
connection with this device a cut-off switch for the driving motor 
can be furnished which will stop the motor immediately when trouble 

Due to the increased use of substandard film for all purposes for 
which the smaller film is sufficient, during the last year a great number 
of film treating and film printing equipments were developed. The 
Union Tonfilm maschinenbau und Vertriebs-Gesellschaft in Berlin 
have marketed an optical reduction printer (35-mm. to 16-mm.), 
an optical printer for 16-mm. film, a contact printer for 16-mm. 
film, and a reproducing and cutting table for 16-mm. sound-film. 

Regarding the brightness of the pictures in the theaters, certain 
progress was made during the past year that is especially interesting 
in connection with the efforts made by Opticolor and Siemens & 
Halske in introducing the lenticular film in the theaters. During 
the Olympic Games the Siemens-Berthon color-film was shown for 
the first time, and it was reported that the satisfactory brightness of 
the projected pictures was due to the design of a new lamp. 

In the processing field, Arnold & Richter constructed fully auto- 
matic developing machines for 35-mm. film with different footage 
capacities. They also constructed for 16-mm. film a fully automatic 
machine in three different sizes, which can be used also for processing 
8-mm. film. 

In the field of substandard cameras, Siemens & Halske have intro- 


duced the Siemens Kino Camera F, using lenses of various manu- 
facturers. Zeiss-Ikon have improved their Movikon 16 to include 
such features as an automatic range-finder, four speeds, polarization 
screen, and motor instead of spring drive. 

One of the outstanding developments of the year has been the intro- 
duction of the Zeiss-Ikon Movikon 8 camera, which is an improved 
construction of the former Movikon 16. This camera can be used 
for double-8 film as well as for normal 8-mm. film. Some of its fea- 
tures are a Sonnar lens of the speed 1 :2 and focal length of 1 cm. in 
Fis-focusing-mount (depth of focus from 1 meter to infinity at greatest 
diaphragm). The bayonet mount provides for using additional 
lenses, e. g., 2.5- and 7.5-cm. focal lengths. Portrait-attachments and 
yellow filters are available. The apparatus has three speeds: 8, 16, 
and 64 frames per second. A single-picture device is also provided. 
The spring motor of the pull-down allows a run of 3 3 / 4 meters of 
film. A scale at the side wall and in the finder of the camera gives 
information about the reserve of the spring motor expressed in terms 
of the unexposed length of film. The picture area of the finder 
corresponds to that of the 1-cm. lens; for the 2-cm. lens an insertion 
mask is provided. Siemens & Halske placed upon the market the 
Kino Camera C8 for cassettes, which can be used with the Kodak 
daylight spools. This camera is provided with a Busch-Glaukar 
Anastigmat 1:2.5, 1.3-cm., and can be used for Cine Kodak 8 film 
(for black-and-white) or for Cine Kodak 8 Kodachrome on the 
usual 7.5-m. spools inserted into Siemens cassettes. Four speeds 
(8, 16, 24, and 64 frames per second) are provided. 

The firm of Niezoldi & Kramer have supplied a low-priced camera 
for Kodak 8-mm. film, and a new model B Cine Nizo 8E, having a 
speed of 8-64 frames and interchangeable lenses, as well as a Cine 
Nizo 8 ZD which takes 7.5- and 15-m. daylight spools of double 
8-mm. film, and permits speeds of 8 to 100 frames per second. 

In the field of substandard projectors Siemens & Halske have 
constructed a "Two-Film Standard Projector" for 16- and 9.5-mm. 
film. Only the masks for the gate and the sprockets need be ex- 
changed; otherwise the construction is the same as that of the 
Siemens standard projector for 16-mm. film. Features include the 
Siemens beater pull-down mechanism, interchangeable projection 
lenses (Meyer Kinon Superior/, 3.5-, 5-, or 6.5-cm.), interchangeable 
two-blade or three-blade rotating shutter; an efficiency of 130 lumens 
with the two-blade rotating shutter and a 5-cm. lens; single-frame 


device ; adjustable speed ; and it can be used on direct current or 
alternating current lines of the usual voltage. 

Eugen Bauer announce that their substandard sound film repro- 
duction equipment is available with Bauer sound head and Bauer- 
Lorenz amplifier. The reproducer is provided with a rotating sound 
drum and flywheel similar to the Roxy equipment. A special micro- 
lens with an optical slit is provided. The apparatus is available 
for 16- and 17.5-mm. film. 

The firm Union, G. m. b. H., placed upon the market during the 
last year a new substandard film projector "Gigant," which reaches 
an efficiency of more than 150 lumens with a 23-volt, 5.3-ampere 
projection lamp. The very simple internal construction of the pro- 
jector is of special interest. 

Also the firm Lytax-Werke improved their well known substandard 
sound-film projector which is also characterized by its very simple 
construction but which nevertheless is very stable and very suitable 
for operating for long periods. 


1 Amer. Cinemat. (May, 1936), p. 218; (June, 1936), p. 264; (Sept., 1936), 
p. 396; (Nov., 1936), p. 483. 

2 "The New Agfa Process of Colour Photography," Phot. Jour. (Dec., 1936), 
p. 612. 

3 Amer. Cinemat. (June, 1936), p. 264. 

4 MEYER, H.: "Describing Agfa's Infrared Film," Amer. Cinemat. (May, 
1936), p. 194. 

8 EARTH, W.: "A Film Emulsion for Making Direct Duplicates in a Single 
Step," J. Soc. Mot. Pict. Eng., XXVII (Oct., 1936), No. 4, p. 419. 

6 DERSCH, F., AND DURR, H.: "New Method for the Dry Hypersensitization 
of Photographic Emulsions," J. Soc. Mot. Pict. Eng., XXVIII (Feb., 1937), No. 2, 
p. 178. 

7 CHARRIOU, A., AND V ALETTE, S. : "Influence of Water on the Sensitivity of 
Photographic Emulsions," Comp. Rend., 202, (April 29, 1935), No. 18, p. 1528. 

8 Rolleau, M. : "Influence of Temperature on the Sensitivity of Photographic 
Emulsions," Comp. Rend., 202 (March 9, 1936), No. 10, p. 835. 

9 STEIGMANN, A. : Phot. Ind., 34 (Jan. 1, 1936), p. 10. 

10 MARNINESCO, N.: "The Law of Blackening of Photographic Plates by 
Supersonics," Comp. Rend., 202 (March 2, 1936), No. 9, p. 757. 

11 MIKHAILOFF, V. I., AND KNAPPE, V. A.: "The Opening of the Experimental 
Factory at Kazan," Photo-Chem. Ind. (1936), No. 1, p. 40. 

11 Kino-Photo Res. Inst. (Moscow), 3 (1935), p. 14. 

13 HAMER, F. M., AND FISHER, N. I.: Proc. Roy. Soc., 154A (May 1, 1936), 
p. 703. 

14 BEILENSON, B., AND HAMER, F. M. : /. Chem. Soc. (Aug., 1936), p. 1225. 


15 /. Amer. Chem. Soc., 57 (Dec., 1935), pp. 2480, 2488, 2492. Ibid., 58 (April, 
1936), pp. 659, 662. 

14 MEES, C. E. K.: "Sensitizing Dyes and Their Applications to Scientific 
Photography," Proc. Roy. Inst. Great Britain (Jan. 31, 1936). 

17 Report of the Progress Committee, /. Soc. Mot. Pict. Eng., XXVII (July, 
1936), No. 1, p. 3. 

18 Amer. Cinemat., 17 (Sept., 1936), p. 370. 

19 Photographische Industrie, 34 (May 27, 1936), p. 608. 

20 Photo. Korr, 71 (Dec., 1935), p. 158. 

21 J. Soc. Chem. Ind., 55 (Apr. 24, 1936), p. 319. 

22 Report of the Progress Committee, /. Soc. Mot. Pict. Eng., XXVII (July, 
1936), No. 1, p. 45, 

** DIMMICK, G. L. : "Improved Resolution in Sound Recording and Printing 
by the Use of Ultraviolet Light," J. Soc. Mot. Pict. Eng., XXVII (Aug., 1936), 
No. 2, p. 168. 

24 BATSEL, C. N. : "A Non-Slip Sound Printer," J. Soc. Mot. Pict. Eng., XXIII 
(Aug., 1934), No. 2, p. 100. 

25 OLSON, H. F. : "A Unidirectional Microphone," J. Soc. Mot. Pict. Eng., 
XXVII (Sept., 1936), No. 3, p. 284. 


Summary. Among the projects under consideration by the Committee during the 
past six months are those of screen brightness; its desirable values and methods of 
measuring it; the question of using a visual test-pattern for checking screen illumina- 
tion; revisions of the projection room plans; questions of projector motors and 
take-ups, and difficulties incident to the starting of projector motors; requirements 
of sound screens; and a recently initiated survey of theaters throughout the United 
States to determine not only existing conditions of projection, but also for the pur- 
pose of establishing a set of recommendations regarding theater structures. 

Many of the projects engaging the attention of the Committee have 
been under consideration for a long time, some of them for several 
years. The original plans for the projection room were drawn in 
1930, and have been revised several times since. The study of screen 
brightness has also continued for several years, concurrently with an 
intensive study of all phases of the subject by the Projection Screen 
Brightness Committee, which this year has been merged with the 
Projection Practice Committee. In addition, a number of new proj- 
ects have been undertaken, but the work on these has not progressed 
sufficiently to warrant formal report. This report will be devoted 
only to those subjects that have been developed to such a point as to 
make a report worth while. 

In prosecuting the work of the Committee it has been found ad- 
visable from time to time to delegate specific projects to sub-commit- 
tees appointed especially for the purpose at hand. The active sub- 
committees at the present time are as follows : 

Adoption of Projection Room Layouts as Standard ; 
Projector Output and Screen Illumination 

(including means of measurements) ; 
Suprex Lamp Magnification Ratio; 
Motor-Starting Time, Types of Take-Up ; 
Technical Coordination; 
Theater Structures; 
Fire Hazards. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received May 
10, 1937. 



It was with deep regret that the Committee learned of the death of 
Rudolph Miehling on April 7th. Mr. Miehling had long been an 
active member of the Committee, and had contributed very substan- 
tially to its work. His loss is keenly felt by his friends and co- 


This subject was studied at length by the former Projection Screen 
Brightness Committee and more recently by the present Projection 
Practice Committee. The latter Committee at a meeting in Novem- 
ber, 1936, approved the recommendation 1 of the Projection Screen 
Brightness Committee to the effect that the brightness at the center of 
a motion picture screen be held within the range of 7 to 14 foot-lam- 
berts. However, in taking this action, the Projection Practice Com- 
mittee desires to qualify its approval by calling attention to the fol- 
lowing considerations. 

Many factors enter in practice to influence the physiological re- 
action to light stimuli. Some of these were discussed in the Projec- 
tion Screen Brightness Committee's report published in the August, 
1936, issue of the JOURNAL. The Projection Practice Committee 
cites the following factors as being of first-order importance in this 
connection. The desirable screen brightness will depend upon the 
density of the print; whether the picture is black-and-white or color, 
the visual state of the audience upon entering the theater; the color, 
width, and brightness of the screen frame and masking; the immediate 
surroundings of the audience including the location; direction, color, 
and intensity of the auditorium illumination ; and the color of the pro- 
jection illumination source. In addition to the foregoing, there are 
various other second-order factors. 

Therefore, it will be appreciated that extreme conditions may 
exist when 7 foot-lamberts may be more than sufficient, while at other 
times 14 foot-lamberts might not be adequate. The report of the 
Projection Screen Brightness Committee previously mentioned has 
emphasized some of these thoughts. With this explanation of its 
reservation, the Projection Practice Committee heartily concurs with 
the findings of the former Committee and believes that their report 
represents an important advance with respect to the subject. 

The Projection Practice Committee will" continue its investigation 
of the practical aspects of screen brightness in theaters, reporting 
upon its findings as developments warrant. 



The function of the Sub-Committee of the Projection Practice 
Committee, to which the study of this subject was assigned late in 
1936, is to recommend specific apparatus and technic for studying the 
practical illumination problems of the motion picture screen with 
respect to the following : 

(1) Brightness (upper and lower limits) 

(2) Optimal screen size 

(5) The effect upon the eyes of the viewer of the color characteristic of the 

(4) Auditorium lighting conditions 

(5) Resolution of detail and contrast value. 

These items involve many factors; for example, both the intensity 
and the color of the light reaching the viewer's eyes depend upon the 
nature and the intensity of the light-source in the projector and the 
reflection and color characteristic of the screen. The optimal size 
of the screen, while primarily dependent upon the viewing distance, 
must also be related to the available illumination. The net effect 
upon the viewer's eyes will depend upon his state of fatigue, the am- 
bient illumination, print density, and other considerations. 

A study of the light intensity reaching the viewer will require re- 
search involving viewing motion pictures at various intensities and 
determining the effects produced thereby upon the eyes of a number of 

Relative to the selection of means for the measurement of illumina- 
tion, both incident upon, and reflected from the screen, extended 
study has indicated the virtual inability to repeat or check measure- 
ments of this character when made with any of the recognized com- 
mercial or laboratory measuring instruments now available. There- 
fore, it is the view of this Committee that careful consideration should 
be given to the characteristics required in a measuring device to be 
suitable for making illumination measurements of projection light- 
sources and light reflected from motion picture screens. A brief 
summation of the more important considerations follows : 

(2) Extensive comparisons have demonstrated that the response characteris- 
tics of commercial light-sensitive instruments depart significantly from the re- 
sponse characteristics of the average eye. Hence, spectral composition becomes 
a variable which is likely to affect unduly measurements of such incident and re- 
flected light. 

(2) While in specific instances rather wide limits of measurement accuracy 
can be tolerated in determining whether the conditions prevailing are satis- 


factory for an audience, it is believed that a tolerance limit of =*=5 per cent will be 
required in meters or instruments used for measuring the light performance of 
projection equipments in different theaters. The interest of one or more of the 
commercial instrument manufacturers experienced in the development of il- 
luminometers is being sought in an effort to bring about the development of a suit- 
able meter. 

Before such an instrument can be designed and manufactured, 
specification requirements must be determined that will satisfy the 
following considerations : 

(1) The instrument shall provide, for the various types of light-sources en- 
countered in projection rooms, consistent luminosity measurements that are 
proportional to the visual effect of the light upon normal eyes. 

(2) The meter shall be of such dimensions and rugged construction as to be 
portable and capable of withstanding the handling necessary to its use. 

(3) Obviously, the cost of the meter must be such as to promote its wide- 
spread use throughout the industry. 

Evidently the nature and present status of the problem as outlined 
prevent drawing final conclusions at this time. Rather, the Com- 
mittee proposes to canvass various individuals and companies having 
potential interest in the problem with the object of organizing a 
study in a logical and orderly fashion to gain the greatest possible 
contribution for the common good. 

It should be appreciated that the development required will prob- 
ably prove costly and extensive. Some lengthy period of time may be 
necessary in which to accomplish it. However, it is believed that 
instruments capable of the performance desired will be produced 
ultimately. One of the first requisites indicated by this situation is 
the creation of a general interest among technical organizations 
whose contributions will accelerate the development. 


The plan was suggested of designing and preparing a suitable film 
containing a visual test pattern for projection in theaters to determine 
whether a projected light falling upon the screen is satisfactory for 
best viewing conditions. A study of the problem included a review of 
the reports and papers published in the JOURNAL by various individuals 
and by the Projection Screen Brightness Committee. 

The consideration of the design of a test pattern included the follow- 
ing factors: 

(1) Weber-Fechner Law 

(2) Range of print densities 


(5) Type of test pattern 

(4) Uniformity of illumination over the surface of the screen 

(5) Effect of visual acuity of the observer upon use of the test pattern. 

A plot of the just-perceptible brightness difference A B, expressed as 
a fraction &.B/B (the Weber-Fechner fraction) has been published 
in the JOURNAL 2 for a natural pupil, with logio B (in foot-lamberts) 
as abscissa and for a 3-degree field. This plot provides the means 
for calculating the step densities of the test pattern. A film con- 
taining these step densities would require the most accurate and 
careful control of exposure and film processing. There is serious doubt 
whether such control could be realized. 

The range of densities to be covered should be taken from 3.2 to 
0.19. 3 These values are the highest -D max . and the lowest D msLX 
measured on a large number of release prints by the Projection 
Screen Brightness Committee. 

The type of test pattern must be one that would give the greatest 
number of step densities at various absolute values of density for all 
parts of the screen. Probably the most convenient would be one in 
which the screen was divided radially from the center in either eight 
or sixteen sectors. Each sector would have the density steps arranged 
radially and the density steps of the different sectors staggered to 
provide each portion of the screen with as many density steps as 

Assume that it were possible to make a test pattern as described, 
and in accordance with the Weber-Fechner Law, it would still be of 
little use since the illumination on the screen is not uniform. The 
brightest portion is at the center and decreases toward the margins. 
The reduction of the marginal illumination depends upon the focal 
length and type of projection lenses used. Hence the design of a test 
pattern must of necessity take these facts into account, in addition to 
many other variable factors. 

Finally, no two observers would see the same results due to their 
differences in visual acuity. 

It was deemed advisable to include this negative report in the hope 
that a different method of attack may be devised by someone which 
will lead to a solution of this problem. 


As was previously mentioned, a partial revision of the projection 
room plans published in the November, 1934, issue of the JOURNAL 


was made, and although the revisions were not sufficiently extensive 
to warrant republication in the JOURNAL at this time, several thousand 
copies of the revision were prepared in pamphlet form for distribution 
to interested persons and organizations throughout the world. The 
intention of the Committee was to distribute this report as widely as 
possible in order to arouse a realization throughout the country of the 
great lack of uniformity in regulations pertaining to motion picture 
projection in theaters, and to attempt to enlist the assistance and so- 
licit the suggestions and criticisms of law enforcement and fire preven- 
tion departments of states and municipalities, so as eventually to be 
able to draw up a model set of regulations that can be recommended to 
the law-making bodies throughout the country. 

Letters directed to the various States of the Union indicated con- 
siderable misunderstanding regarding the purpose of the booklet, and 
it was accordingly ruled by the Committee that the following caption 
be imprinted upon the covers of the pamphlets in order to clarify the 
situation : 

"The material herein presented is recommended practice for new theaters, 
and for alterations of existing theaters. It is not to be proposed as obligatory for 
existing theaters." 

This provision must be clearly appreciated in view of the fact that 
certain differences exist between some of the recommendations con- 
tained in the pamphlet and certain regulations of the National Fire 
Protection Association. Further study of projection room and pro- 
jection conditions is being conducted with the possible view of pre- 
paring a set of practical regulations reconciling these differences. 


Difficulties encountered in projection with regard to motors and 
take-ups are: 

(a) Fast starting of the projector motor, which strains the gears 
and damages the film; 

(6) Irregular action of the take-up, with the result that jerks are 
transmitted to the film, tending to tear the sprocket holes at the hold- 
back sprocket. If the pad roller on the hold-back sprocket is of the 
single-roller type and the jerk of the film is excessive, the film is likely 
to be damaged and jerked from the sprocket entirely. 

Jerking of the film may be caused either by rough action of the 
clutch, slippage in the drive of the belt types, or slack in the drive in 
either the belt or chain type of take-ups. 


Either the adoption of the following specifications as standard or 
the submission of them to the manufacturers of projection equipment 
should help considerably in reducing the difficulties outlined above. 

Motor-Starting. Experience shows that a starting time of two to 
three seconds seems to be quite satisfactory. The acceleration of the 
equipment from zero to full speed should be approximately steady, 
and under no circumstances should have a break in the speed-time 
characteristic. This latter point is mentioned because the use of a 
resistor in the starting winding for slow starting, and short-circuiting 
this resistor as the motor comes up to speed, is likely to cause a jerk 
in the equipment at the time the resistor is shorted. 

Take- Ups. The design of take-ups should be such that the pull of 
the film is steady at all times, irrespective of the amount of film upon 
the take-up reel. 

It is preferable to use double pad rollers on the hold-back sprocket 
to insure that the film stays upon the sprocket at all times. 

Projectionists using the equipment can reduce film damage by mak- 
ing certain that the film is not slack between the take-up reel and the 
hold-back sprocket before starting the projector. 


The accepted practice and requirements with regard to the trans- 
mission of sound through motion picture screens have not undergone 
any appreciable changes since they were established during 1930 and 
1931. The only major difference refers to the losses allowed at the 
higher frequencies. 

The screens in common use at the present time are those in which 
the sound waves are transmitted through the air spaces in the screen 
material. These air spaces may be either the pores of the material or 
perforations punched into the material. 

Because of optical characteristics of the screen material, the per- 
forations or air spaces should be as small as possible and the number 
of perforations a minimum. 

As a result of tests, it was decided to limit the aggregate open area 
for the screen to 7.5-10.0 per cent of the total screen area. The ratio 
of the thickness of the screen material to the area of a single opening 
should be very small, because the air in the individual air passages 
presents a mass reaction to the flow of sound energy. 

The frequency response of a screen enters into the determination of 
its suitability from an acoustical standpoint. No serious trouble is 


experienced with regard to the low-frequency response but a drop 
occurs at the higher frequencies. 

Losses at various frequencies were limited as follows : 

4.5 decibels at 10,000 cps. 
2.5 decibels at 6000 cps. 
0.5 decibels at 1000 cps. 

Each of these figures represents an average value taken from mea- 
surements having no variations due to testing procedure that exceed 
plus or minus 2 db. 

On the whole it is quite difficult to set definite limits for screen 
transmission to cover all possibilities, but if the tolerances given above 
are adhered to, efficient results will be obtained. 


In order to obtain information that would assist in the study of 
screen brightness and various other matters, such as projection 
angles, seating areas, general lighting, in addition to a number of 
projection and screen characteristics, a chart was drawn up containing 
skeleton diagrams of the vertical and horizontal plans of a theater. 
Several thousands of these charts have been distributed among a 
number of large companies of the industry whose engineers are assist- 
ing in obtaining the dimensions requested on the chart. A reproduc- 
tion of the chart is shown in Fig. 1. Accompanying the charts dis- 
tributed were letters describing its purpose. 

The theaters covered in the survey include all classes, both as to 
size and general construction, and there will be sufficient representa- 
tion of the entire industry to permit a very reliable analysis of condi- 
tions to be made. Instead of mailing the charts directly to the man- 
agers of theaters, it was felt that the results would be more reliable if 
the measurements were made and the charts filled out by men experi- 
enced in such work. Accordingly, the field men and the management 
of RCA Manufacturing Co., International Projector Corp., Electrical 
Research Products, Inc., National Carbon Co., Inc., Forest Electrical 
Co., Bausch & Lomb Optical Co., and National Theater Supply Co. 
are all to be thanked for their cooperation. In addition, a number of 
charts were distributed to the delegates at the Convention of the 
M. P. T. O. A. at Miami in March and the additional information de- 
rived therefrom will probably be very helpful. As it will probably 
require consideration time to make a thorough analysis of charts that 



are returned, it may not be before the October Convention of the 
Society that the Committee will be able to render a report on its 

Hotel Penn.ylianla N e York City 


envelope provided. 



Question No, 1. 

Uuestlon No. 5. 

Dimension A should be klilte Picture WIDTH. 

AC Volts 

Dimension L should be Width of Proscenium 

Question No. 8. 

*ie_lion o. 3. 

Question No. 7. 


Question No. 8. 

Question No. 3. 

of theatre. 
Question No. 9. 

A- Beaded or metallic 

i - lltlier-Uescrlbe 

Question No. 4. 

Check type of proje tlon llgiit source In use. 
A- Lo Intens ty Anps. 

11- High Inten ily 
1) HlKh- o (Heflector) 

2) Conde ser Type 
3) Supre 

Fora ~~~ 


A.C. Arc 

riojicTioi rocTicc COHHITTK 

FIG. 1. Theater survey chart. 

With the information thus obtained, the Committee hopes even- 
tually to be able to construct plans for various types of theaters, just 
as they have been able to construct plans for projection rooms. 



These plans are to include schedules of screen sizes, screen brightness, 
and other matters of importance to architects and others engaged in 
building new or altering existing theaters. 


In view of the fact that devices have been placed upon the market 
by means of which projectionists may place upon films cue marks for 

change-overs, the following reso- 
lution was adopted by the Com- 
mittee at its meeting in January : 

Guided Edge 


"The Projection Practice Committee 
of the Society of Motion Picture Engi- 
neers does not approve any structural 
modification, injury, or mutilation of 
the Standard Release Print by the 
projectionist, and views with disfavor 
the sale of devices capable of causing 
physical damage to the film for cue 
marks or the like. The Committee 
regards cue-marking as a function ex- 
clusively of the laboratory." 


Since the adoption of the 
standard camera and projector 
apertures by the industry several 
years ago, these standards have 
not fulfilled the requirements for 
which they were created, due to failure to take into consideration 
the masking at the theater screen. 

To overcome objectionable blocking out by the screen masking of 
important parts of the photographed action, it is recommended that 
action being photographed be limited to an area 0.005 of an inch 
smaller on all sides than the dimensions of the standard projector 

The following will outline in general the differences between the 
camera and projector apertures: 

Camera 0.868 0.002 inch wide 
0.631 0.002 inch high 
0.744 =*= 0.002 inch center-line from guided edge. 


2. Recommended area 
photographed action. 



Projector 0.825 ="= 0.002 inch wide 
0.600 =*= 0.002 inch high 
0.738 0.002 inch center-line from guided edge. 

It has been found from experience that, on a 9 by 12-foot screen at 
an angle of projection of approximately 15 degrees, a 1-inch masking 
around the screen into the projected picture has proved sufficient to 
assure proper projection. 

This 1-inch masking represents a decrease of 0.005 inch approxi- 
mately on each side of the projector aperture, or an aperture 0.815 
inch wide by 0.590 high, 0.738 0.002 inch from center-line to guided 
edge (Fig. 2). 

The Committee recommends, in view of the facts given above 
and in order to avoid loss of portions of the picture, that cameramen 
and studio laboratories provide their camera-focusing devices and 
view-finders with a working ground-glass having a rectangle of the 
conventional thin black line corresponding to the dimensions 0.815 by 
0.590 inch, as an aid to the cameraman in composing his picture. 

The Committee also recommends that a minimum masking or 
overlapping of the projected film image upon the screen be established. 
For example, on a 9 by 12-foot screen the masking should not 
overlap the projected picture more than one inch on each side; for 
smaller or larger screens this masking or overlapping on each side 
should be of the same approximate ratio. 

H. RUBIN, Chairman 











1 Report of Projection Screen Brightness Committee, /. Soc. Mot. Pict. Eng., 
XXVII (Aug., 1936), No. 2, p. 127. 

2 /. Soc. Mot. Pict. Eng., XXVI (May, 1936), No, 5, p. 517. (See Fig. 3.) 

3 /. Soc. Mot. Pict. Eng., XXVI (May, 1936), No. 5, p. 551. (See Table II.) 


Summary. With the recent reorganization of the Committee representation was 
effected from all the important exchange companies, in addition to the theater and 
laboratory branches of the industry, which gives the Committee close contact with all 
the important factors in which it may at any time be interested. 

The attention of the Committee is restricted to the physical handling of film in ex- 
changes, questions of safety and fire prevention, technic and supervision of inspection, 
uniformity of exchange practice, and the like. 

Projects have been initiated for drawing up plans for an ideal exchange, for pre- 
paring an instructional booklet for exchanges, and for producing a descriptive film 
to supplement the booklet. 

The Committee on Exchange Practice was originally formed in 
July, 1932, under the Chairmanship of Mr. Trevor Faulkner. Regu- 
lar reports were submitted to the Society each year, a list of which is 
appended to this report for reference. 

At the beginning of 1937 a reorganization of the Committee was 
effected, the new members consisting of the heads of the various 
New York City Exchange Departments, so that a closer contact 
could be maintained with the very branch of the industry that would 
be most interested in the work of this Committee. In order to 
show this relation, the list of members of the Committee is given 
herewith, together with their company affiliations : 

A. W. SCHWALBERG, Chairman (Warner) 

O. C. BINDER ( Universal) H. A. MERSAY (20th Century-Fox) 

A. S. DICKINSON (M. P. P. D. A .) N. F. OAKLEY (Dupont) 
G. K. HADDOW (Paramount) H. RUBIN (Paramount) 

H. C. KAUFMAN (Columbia) A. SCHUBART (R. K. O.) 

J. S. MACLEOD (M-G-M) J. H. SPRAY (Ace Labs.) 

It is with deep regret that the Committee records the death of 
one of its most active members, J. P. Skelly, on March 8, 1937. 

It will be noted that in addition to having representation among 
the various large companies, the Conservation Department of the 
M. P. P. D. A. through Mr. Dickinson, the Laboratory branch of the 
industry through Mr. Spray, as well as a film manufacturing com- 
pany through Mr. Oakley, are represented. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received May 
12, 1937. 


During the past season meetings of the Committee have been held 
every month at the offices of the M. P. P. D. A. Minutes of the meet- 
ings have been prepared and circularized by the Secretary of the 
Committee, Sylvan Harris, and it is the plan of the Committee to 
continue its meetings regularly during the entire year. This, the 
first report of the new Committee, will be followed in due course by a 
detailed description of the Committee's accomplishments at the next 
Convention in October. 

The first meeting of the new Committee was held on February 25th, 
at which time the agenda and scope of the Committee were estab- 
lished. The attention of the Committee is restricted to the physical 
handling of film and not to subjects relating to advertising accessories, 
accounts, sales, or the like. Other problems facing the Committee 
refer to safety and fire prevention, the technic and supervision of 
inspection, methods of "processing" film, and uniformity of exchange 

The question of uniformity of exchange practice and technic have 
been receiving the close attention of the Committee for some time, 
particularly with reference to the relation between the laboratory 
phase and the projection phase, referring to the state in which film 
is received by the exchanges from the laboratories and sent by the 
exchanges to and received from the theaters. In this connection, it 
is important to note that the Chairman of the Projection Practice 
Committee of the SMPE, Harry Rubin, has been made a member of 
this Committee. 

Considerable attention has been given to the subject of rewinding 
films in exchanges and the manner of making patches. It was the 
decision of the Committee that in the interests of uniformity it would 
be best to supply films to the theaters wound with the heads out, 
despite the fact that this would lead to a slight problem in Chicago, 
in view of the requirement in that city that the projectionists use 
14-inch reels, making it necessary to rewind the film from the reels 
supplied by the exchanges. Exception must therefore be made in 
the Chicago area, in supplying the films wound with the tails out. 

Steps have been taken to improve the uniformity of printed mate- 
rial accompanying films shipped out by exchanges, in respect to reel- 
bands, labels, etc., the idea being to make the information contained 
thereon more uniform and explicit. 

A plan has been formulated to prepare an instruction booklet, 
under the auspices of the Committee, for distribution among ex- 


changes, which would describe in more or less detail the proper way 
to inspect and handle film. Such a booklet was prepared some time 
ago for use in Paramount exchanges, but the plan is to prepare a 
more up-to-date and complete guide for the exchange personnel than 
was available in the Paramount booklet. 

Steps have been taken also to draw up plans for an ideal exchange, 
probably in a form somewhat similar to the plans drawn up by the 
Projection Practice Committee some time ago for motion picture 
projection rooms. These plans will describe, in general terms, the 
recommended construction of the exchange; specifications for the 
equipment ; and proper method of operation, including housekeeping 
and general maintenance. The plans will also contain general 
information relating to the problems of supervision, working condi- 
tions, the advantages of avoiding confusion and noise, the impor- 
tance of adequate light and ventilation, cleanliness, etc. 

Another project that will undoubtedly turn out to be of great 
importance to the exchange branch of the industry is that of preparing 
a demonstration film, under the supervision of the SMPE Exchange 
Practice Committee, which would show the proper procedure to be 
followed in inspecting and handling film in the exchanges. This film 
will complement the instructional booklet described above. The 
scenario for the film is now being prepared, and it is probable that 
shooting will begin within the next month or so. The purpose would 
be to provide prints of the film to exchanges, as needed, for showing 
at their various branches in order to instruct their employees. How 
often such showings will be necessary will, of course, depend upon the 
needs of the exchanges and upon the turn-over of their personnel. 
The film will tell a running story, the comments being made either 
in the form of a running narrative or as remarks by the various actors 
in the picture. 

The items described are the more important ones facing the Com- 
mittee. In addition, however, there are a number of other items 
that do not warrant a report at this time in view of the fact that work 
upon them is just being initiated. However, it is expected that by 
the time of the Fall Convention in October a very complete report 
of the year's work will be available; and in view of the fact that the 
members of the Committee are those in charge of the various ex- 
change circuits, it is anticipated that the improvements in procedure 
and uniformity that will be agreed upon by the Committee will be 
put actively into effect in the exchange branch of the industry without 


delay. However, close collaboration with other branches of the 
industry is desired in view of the fact that the exchange branch repre- 
sents only one link in a long chain, and the procedure adopted in the 
exchanges is dependent to a large extent upon the materials supplied 
to the exchanges and the manner in which the film is handled in the 

Reports of the Exchange Practice Committee: 

/. Soc. Mot. Pict. Eng., XX (March, 1933), No. 3, p. 199. 
Ibid., XXH (May, 1934), No. 5, p. 332. 
Ibid., XXV (Nov., 1935), No. 5, p. 462. 


Summary. The Eastman perforation, although adopted by the Society as a 
standard for positive and negative film, has certain disadvantages for use in con- 
nection with color processes and for background projection. The reasons for these 
limitations are analyzed, and a proposal is made that the important advantages of 
the Eastman filleted rectangular shape be retained in a perforation, the dimensions 
of which are the same as those of the Bell & Howell perforation. Such a perfora- 
tion would fit existing Bell & Howell registering pins. 

The use of a photocell having most of its sensitivity outside the visible spectral region 
imposes an added burden to those "working upon color sound processes. Search is 
urged for a cell that would have all the advantages of existing caesium cells but with 
its chief sensitive response in the visible range. 

The term "Direct Color Developer Process" is recommended for a color process 
wherein non-diffusing color-formers in the emulsion (multiple-layer) combine with 
the oxidation products of the developer to form insoluble dyes. A process of this type 
was introduced recently by Agfa. 

Perforation Standards. Prior to 1930, the industry was using what 
is known as the Bell & Howell perforation for both negative and posi- 
tive stocks. The overall dimensions of this perforation are 0. 1 10 inch 
wide by 0.073 high, and the shape is such that the rounded ends of the 
perforation lie upon a circle. 

In the fall of 1930, the Society adopted a new standard perforation 
for positive film only, the shape of which is a filleted rectangle of di- 
mensions 0.110 inch by 0.078. This shape and size are usually referred 
to as the Eastman perforation, because it was introduced by the East- 
man Kodak Company some years earlier. This new standard for 
positive film has been adopted by the black-and-white industry gen- 
erally; however, it has not been adopted by any commercially oper- 
ating color process. All color prints being commercially produced 
today have the old Bell & Howell standard perforation. The reason 
is, of course, the necessity in present-day color processes of transfer- 
ring accurate register from negative to positive by means of regis- 
tering pins. This means that at least the overall dimensions of the 
perforations in negative and positive must be the same. 

In November, 1934, the Society adopted the Eastman perforation 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received April 
15, 1937. 


as standard for negative as well as for positive stock but there is no 
indication, either here or abroad, that this new standard for negative 
stock will actually be accepted; in fact, it appears that it will not be 
accepted. There are several reasons for this. For example, steadi- 
ness in background projection requires transfer of registration of pic- 
tures with respect to sprocket holes from the negative to the print, 
and the use of registering pins in the projector. It is universal prac- 
tice in the black-and-white industry to use Bell & Howell perforations 
even in the positive prints used in this type of work. Much of the 
negative material used in background projection conies from "stock 
shots," all of which, of course, already have the Bell & Howell perfora- 
tions. A third reason is that the confusion that would result during 
the change-over period might result in cases wherein film containing 
the small perforations encounters large-size pins either in camera, 
printer, or projector. In such a case, jamming and damage to the 
film would result. While it might be possible to re-perforate the old 
negative to the new standard, and, further, so to organize the period 
of transition as to minimize trouble, the fact remains that the industry 
has taken no step to adopt the Society's recommendation on Novem- 
ber, 1934. The Society now finds itself in the rather unfortunate 
position of having approved, in November, 1934, a standard that the 
industry has refused to accept in practice. From the point of view of 
the present-day color processes, even the standard adopted in 1930 
for positive stock is impracticable. 

The reason for adopting the increase in the vertical dimension in the 
case of the Eastman perforation was to allow additional clearance on 
projector sprockets to compensate for film shrinkage; but this diffi- 
culty has been minimized in the intervening years by the introduction 
of film bases of less shrinkage than those that were in use at the time 
the Eastman perforation was promulgated. Furthermore, the sound 
revolution has caused a very great increase in the care taken inmechani- 
cal maintenance of equipment in the theater projection room. 

Now it is believed, and such tests as have been made substantiate 
the belief, that the very definite and important advantages of the fil- 
leted rectangular shape can be retained in a perforation whose dimen- 
sions are the same as those of the Bell & Howell perforation and will 
consequently fit upon existing Bell & Howell perforation registering 
pins. Such a solution of the problem has previously been urged by 
Mr. Howell. 

While the cost of a change of standards is always great, it never 


grows any less with time, and there is, of course, a not inconsiderable 
current expense to maintain two standards. In view of the fact that 
such standards as have previously been adopted have been found to be 
impracticable both for black-and-white and, especially, for color, the 
Color Committee feels that the Society, through its Standards Commit- 
tee, would do well to examine carefully the possibilities and advan- 
tages of a new universal standard perforation that would be practi- 

Photocell Sensitivity. The Color Committee would like to call the 
attention of those working in sound to the fact that the use in the pro- 
jector of a photoelectric cell such as the caesium cell, having most of 
its sensitivity outside the region of the visible spectrum, requires that 
color processes deal not only with the visible spectrum but also with 
the added region in which the photocell is sensitive. This imposes a 
further burden upon those working in color. Their problems would 
be considerably simplified were the sensitivity of the photocell con- 
fined to the visible spectrum. The sound men themselves would gain 
an advantage also in such a case, due to a simplification of the design 
and accurate focus setting of the optical system in the reproducer. 
We do not mean in any way to urge a return to the potassium cell 
that was in use prior to the advent of the caesium cell but rather to 
urge the search for a cell having all the advantages of the caesium cell 
but with its principal sensitivity within the visible range. In other 
words, the Color Committee believes that the ideal photocell for the 
projector has not yet been developed and it would urge the sound men 
to seek it. 

Further Classification of Color Processes. A further classification of 
types of color processes is needed to take care of the process recently 
introduced by Agfa. In this process, non-diffusing color-formers re- 
side in the several emulsion layers. When the film is developed in a 
coupler-developer these color-formers combine with the oxidation 
products of the developer to form insoluble dyes. The phrase, "direct 
color," has been considered as descriptive of this process, but such a 
phrase might also apply to a bleach-out process. The recommended 
phrase, therefore, to describe the new process is "direct color developer 

J. A. BALL, Chairman 




Summary. A resume is presented of correspondence conducted with the British 
Institute of Cinematography. The report of this organization is abstracted as follows: 
(1) A theoretical analysis of the light losses in a projector rising direct illumination 
is made, showing that for every 100 lumens emitted by the lamp, only 2.43 lumens 
find their way through the projection lens; (2) it is suggested that unit intensity be 
used as a method of comparison between one projector and another and that 1 foot- 
candle be regarded as an average value for home use and 4 foot-candles for small audi- 

Objection is taken by this Committee to the latter proposal, and the opinion is ex- 
pressed that the suggested values are too low. A satisfactory intensity should cover 
projection of adequate quality. 

Attention of the Society is directed to the matter of standardizing the procedure 
for the determination of total screen lumens. 

This Committee is investigating the German recommendations 
concerning standardization of camera and projector sprockets, prin- 
cipally 16-mm., with a view of passing on recommendations to the 
SMPE Standards Committee for further consideration. 

Additional work is being done in the matter of establishing a sat- 
isfactory basis upon which to rate 16-mm. projector performance. 
In this respect, some correspondence has been conducted with the 
British Institute of Cinematography in connection with their initial 
report on the same subject, which appeared in January, 1937. l 
It is felt that the report is sufficiently important to warrant repeating 
its essentials: 

"In a projector, a source of light is enclosed in a lamp house having 
an opening in which is fixed a condenser ; usually, in addition, a re- 
flector is mounted diametrically opposite the condenser. The light 
escaping through the condenser passes through a gate, a shutter, and a 
projector lens. Assuming that the projector is running at normal 
speed, with no film in the gate, what proportion of the light emitted 
from the lamp escapes from the projection lens? Consider the ob- 
vious sources of light loss, working from the projection lens back to 
the lamp. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. 



"(1) The Lens consists of a number of glasses, all of which absorb 
a certain amount of light in themselves and the combination has an 
effective aperture which controls the amount of light passed. 

"(2) The Shutter. Assume a two-bladed shutter with 90-degree 
blades. The light passing to the projection lens is cut by one-half 
during each revolution of the shutter, so that 50 per cent of the light 
output is lost. This is a necessary loss and varies according to the 
type of shutter. 

"(?) The Gate is rectangular in shape and must be evenly illumi- 
nated to the corners so that the diameter of the circle of light passing 
from the condenser must be at least equal to the diagonal of the gate. 
The loss here is therefore equal to the difference between the area of 
the gate and the area of the circle of light whose diameter is equal to 
the gate diagonal. This loss amounts to no less than 40 per cent. 

"(4) The Condenser is of thick glass and absorbs its proportion of 

"(5) The Lamp House. The diameter of the condenser is condi- 
tioned by the diagonal of the gate and its distance from the gate. 
Reverting to our consideration of the candle inside a sphere, it will be 
seen that since the opening in the sphere, or enclosure, is already con- 
ditioned, the light-source must be brought as near as possible to the 
condenser so that the opening in the equivalent sphere is as large a 
proportion of its total area as possible. This, in turn, is conditioned 
by the heat generated by the lamp, because the greater the heat the 
larger must be the diameter of the glass tube, and hence the greater 
the distance of the filament from the condenser. The most efficient 
reflector is a polished silver surface, but, as this surface deteriorates, 
a silvered mirror is preferable over a period of time and will reflect 
not more than 75 per cent of the light incident upon it. 

"Taking these matters into consideration, and assuming that the 
whole of the horizontal candle-power can be directed at the condenser, 
we have, very roughly, one-twelfth of the lamp lumens plus 75 per 
cent of this figure; i. e., all that we can expect to present to the con- 
denser is, very roughly again, some 15 per cent of the total lumens of 
the lamp. This upon the further assumption that the square of the 
distance from the lamp filament to the condenser is not numerically 
greater than the effective area of the condenser opening. 

"Adding up these sources of loss, it is not surprising, therefore, to 
find that the efficiency of a projector measured in terms of the ratio of 
lumens output to lumens input to the lamp house is only of the order 


of 2 per cent. Hence the comparison of projectors by means of their 
true measured efficiency will not convey a great deal, and it is, there- 
fore, advisable to consider some other method. 

"Only projectors with direct lighting have been considered above. 
Those of the indirect type, where the lamp house is at the side of the 
machine and the light issuing from the condenser is reflected at right 
angles to the gate, have an additional light loss due to absorption by 
the mirror. A prism giving total reflection does not entirely over- 
come this loss, as there is still absorption taking place in the glass. In 
view of the other losses, however, this loss is not serious. 

"A summary of the losses in a projector using direct illumination 
can be demonstrated in the following way. The figures given do not 
refer to any particular type or make of projector, but represent a 
purely theoretical case. 

"For every 100 lumens emitted by the lamp: 

15 lumens arrive at the condenser surface, including light reflected by the 

13 . 5 lumens find their way through the condenser; 
4.5 lumens find their way through the shutter; 
2.7 lumens find their way through the gate; 
2.43 lumens find their way through the projection lens. 

"It should be appreciated that with a given projector, the true 
efficiency can be increased in two ways: by the use of a projection 
lens of greater effective aperture, and by the use of a shutter having a 
shorter period of cut-off. The actual light output can also be in- 
creased by using a higher-wattage lamp, or a lower-voltage lamp of 
the same wattage, this latter giving a greater number of lumens per 
watt. But increased wattage in the same lamp house, although giving 
increased light output, generally does so at the expense of efficiency. 
It is usual to express the overall efficiency of a projector in screen 
lumens per watt, and this figure varies from about 0.06 for 8-mm. 
machines to 0.6 for 16-mm. machines. 


"In determining a suitable criterion of screen illumination, consider- 
ation must be given to the practicability of this criterion and to the 
manner in which the customary illumination of screens is affected 
thereby. It is customary in the home, on the one hand, to arrange the 
projection room to be completely dark if possible, and in the profes- 
sional auditorium, on the other hand, it is usually a matter of law to 


have sufficient lighting in the auditorium to enable the audience to 
see its way out in emergency. Conditions in the home and in the 
cinema differ in two respects: 

(a) The home auditorium can be made completely dark, the cinema can not ; and 

(b) The type of film used in the home is usually of the reversal type and 
dense, whereas in the cinema it is of the positive type and, by comparison, thin. 

"It is not beyond the bounds of probability, therefore, that the 
additional light required by reversal film is offset by the additional 
light required in the theater by virtue of the fact that stray emergency 
lighting reaches the screen and tends to dull the picture. 

"The criterion suggested is that of an intensity of one foot-candle 
at the surface of the screen when the screen is illuminated by light 
projected through a piece of film of perfect transparency. This 
means that when a film containing a grading from perfect transpar- 
ency to perfect opacity is projected onto a screen, the light at the sur- 
face of that screen varies from to 1 foot-candle. It may be said 
here that if the screen were evenly lighted by stray light to an inten- 
sity of 1 foot-candle, then the variation of light would be from 1 to 2 
foot-candles, giving a duller picture, but still visible. The amount of 
light reaching the eye from a screen so illuminated depends upon the 
reflecting power of the screen, and the reflecting powers of commercial 
screens will be the subject of a further investigation. In the mean- 
time the suggested criterion can be taken to refer to an average screen 
3uch as is used in the home, having an average reflecting power over a 
fairly narrow angle. 

"At first sight this intensity of 1 foot-candle appears very low, but 
it should be remembered that it is being applied in a special case. 
From a psychological point of view, attention is being focused upon a 
small area, and this represents only a small section of the total area 
that would be taken in by the eye if all objects in the total angle of 
view at that distance were illuminated. It is probable that the eye is 
called upon to do less work when focused at one distance only upon a 
two-dimensional object, and requires less stimulation of light than 
when constantly changing focus and direction and measuring dis- 
tances, as is the case normally. It is suggested that unit intensity be 
used as a method of comparison between one projector and another, 
and that this intensity of 1 foot-candle be considered as an average 
value for home use and that an intensity of 4 foot-candles be con- 
sidered as an average value for small audiences including educational 
use. This is more or less within present practice. 


"It is proposed to classify projectors according to the size of screen, 
rhich will give the intensities mentioned above. 

"Before proceeding to the method of measurement and classifica- 
tion it will be of interest to examine the claims put forward for some 
of the well-known projectors on the market today. The screen lu- 
mens given for the 16-mm. projectors are those published by the 
makers and those given for the 9-mm. projectors are the results of tests. 

"Messers. Siemens claim that their standard projectors have been 
used to show a 16-ft. picture (0.68 foot-candle) to an audience of over 
2000 people, and speak of 21 lux (1.95 foot-candles) as an 'extraor- 
dinary light value.' If we exclude the 13-ft. guaranteed picture of 
the Agfa, which refers to a white screen, and assume that the other 
claims presuppose the use of the best type of beaded screen, then the 
intensities vary from 0.32 to 0.84 foot-candle, and our requirements 
of 1 foot-candle on an average screen appears to be reasonable. 

"R. F. Mitchell 2 has suggested a standard of 6 foot-candles as a 
basis of classification, but this would appear to be impracticably high 
in view of the present output limitations of substandard projectors, 
since one has yet to hear of a 16-mm. projector with an output as high 
as 300 screen lumens,* and even this figure would limit the size of a 
screen to a maximum width of 8 feet. This was only a suggested 
standard, however, and he also said that the corresponding screen 
sizes could be doubled if necessary, i. e., an intensity of 1.5 foot-candles. 
A point of interest, however, is that Mr. Mitchell stated in the discus- 
sion in a previous paper that it was quite usual to show a 12-ft. or 
14-ft. picture to an audience of 1000 or 2000 people with quite satis- 
factory results when using a 750- watt lamp. Now, a Bell & Ho well 
750- watt projector with an //1. 65 lens gives about 210 screen lumens, 
so presumably the audience was satisfied with intensities of 1.95 and 
1.43 foot-candles." 

The Chairman of this Committee has objected to the interpretation 
of this low intensity as being satisfactory, because of the fact that 
many 16-mm. projector manufacturers advertise the possibility of 
showing large-size pictures. A careful definition of the word satis- 
factory has been suggested: "Too often we tend to use this word to 
cover projection of minimum suitability, whereas really it should 
cover projection of adequate quality." The attention of the British 
Institute has also been called to the various papers that appeared in 

* Such a machine is available. 3 



the May, 1936, JOURNAL, and their reply is being awaited with con- 
siderable interest. 

The Committee would like to call the attention of the Society mem- 
bers in general to the matter of standardizing the procedure for de- 
termining total screen lumens. The lack of an approved method in- 
troduces sufficient differences as to hamper, if not prevent, satis- 
factory progress of this rating procedure. 2 This Committee is co- 
operating with the Projection Practice Committee and Standards 
Committee in furthering the establishment of these desirable recom- 

R. F. MITCHELL, Chairman 






1 "The Performance and Classification of Substandard Projectors," J. Brit. 
Inst. Cinemat., (Jan., 1937), No. 1, p. 6. 

2 MITCHELL, R. F.: "Non-Theatrical Projection," J. Soc. Mot. Pict. Eng., 
XXXI (Oct., 1935), No. 4, p. 314. 

J MITCHELL, R. F., AND HERD, W. L.: "1000-Watt 16-Mm. Filmosound 
Projector," J. Soc. Mot. Pict. Eng., XXVII (Oct., 1936), No. 4, p. 440. 


Summary. The membership of the Society is growing steadily at the net rate of 
25 to 30 members a month, the present (April 30, 1937) membership being 1283, with 
30 applications pending. The broadening of the membership to include all the 
important countries of the world, in addition to the domestic membership, is indicative 
of the widening activities of the Society in international motion picture affairs. 

The growth of the membership, although not spectacular, this past 
year has nevertheless been steady and quite satisfactory. During 
1936 the net increase was approximately 25 new members a month. 
Since January 1, 1936, 79 new members have been admitted, 18 old 
members reinstated, and 30 new applications are pending, making a 
total of 127, or approximately 32 a month. 

The net figure, however, is less than that, because of the fact that, 

as every year, there are a few resignations, and this year so far there 

have been five deaths. The net, however, as stated, is very close to 

25 a month. 

The total membership at the present moment (April 30) consists of : 

Honorary 7 

Fellows 140 

Active 328 

Associate 808 

Total 1283 


Pending 30 

Total 1313 

This figure may be reduced somewhat by the middle of the year, 
because at that time members who have not paid their dues for the 
current year will become delinquent. It is expected, however, in 
view of the general improvement in conditions, that the number of 
delinquents this year will not be as great as that of last year, so that 
by the end of 1937 it is anticipated that the net membership in good 
standing will be well over 1400. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. 



It is particularly interesting to note that the foreign membership of 
the Society is increasing as rapidly as the domestic membership. 
This is probably due in part to the broadening of the Society's activi- 
ties through its relations with the foreign standardizing bodies and 
other motion picture engineering societies. 

A similar increase may be noted also with respect to non-member- 
ship subscriptions. For several years the number of non-member 
subscriptions averaged very close to 200. During the past two years, 
however, the number has increased to 364, the net increase during the 
past four months alone being 66. Many of these non-membership 
subscriptions are held by the libraries of large research and industrial 
organizations, and as noted above in connection with membership, 
the increase in non-member subscriptions in foreign countries is par- 
ticularly interesting. 

Although the situation is very promising, and the membership and 
non-member subscriptions have reached new high peaks, it is the de- 
sire of the Membership Committee that there be no relaxation of 
effort to increase the membership further. The Society does not by 
any means cover the entire field adequately, and there are many per- 
sons actively engaged in the motion picture field, even in such a center 
as Hollywood, who could well become members of the Society, to the 
interests both of the Society and themselves. The Membership and 
Subscription Committee seeks the assistance of the entire member- 
ship of the Society in this work. 

E. R. GEIB, Chairman 


Summary. A description of the toning of the entire release of the Metro-Goldwyn- 
Mayer production "The Good Earth," using a modified developing machine, 

Toning a motion picture positive film is an art that has been nearly 
forgotten. For the past decade very little, if any, toning has been 
done. The inception of sound photography with its many compli- 
cated problems probably had a great deal to do with it, but with 
the advances that have been made, not only in sound photography 
but also in laboratory processing, it is not inconceivable that this art 
might be partially revived. 

Many of the emotional moods that motion pictures seek to portray 
can not always be depicted to their full extent by the normal gray 
tone of black-and-white photography, since gray tones can have a 
very sobering effect upon the observer. While gray no doubt en- 
hances certain moods, there are many instances where color of some 
sort would enhance the mood and thereby produce a more striking and 
favorable reaction upon the observer. Much of the early work in 
motion pictures made use of color effects produced by the use of tints 
and tones, either separately or in combination. Every so often a 
picture is made in which definite mood effects are to be depicted that 
could be greatly strengthened by the use of some color medium. The 
choice of the color, as well as the medium, requires very definite plan- 

When consideration was given by Metro-Goldwyn-Mayer to the 
picture The Good Earth it was felt that normal black-and-white 
photography did not convey the desired mood satisfactorily. Search- 
ing for a means to produce the desired effect the subject of toning the 
positive print was given consideration, and after much experimental 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
May 11, 1937. 

k * Metro-Goldwyn-Mayer Studios, Culver City, Calif. 


66 J. M. NICKOLAUS [J. S. M. P. E. 

work a solution of the problem was arrived at, as will be described. 
One of the reasons why it was felt desirable to present the data was 
the fact that to the best of our knowledge this is the first complete 
major release to be toned in its entirety, and, furthermore, it is the 
first picture to be so toned in a modern developing machine. 

It should not be presumed that because the release prints of The 
Good Earth were completely toned, there is a desire on the part of the 
studio to tone other pictures indiscriminately. It must be remem- 
bered that the decision to tone the prints of this picture was not ar- 
rived at with any thought in mind of eliminating color photography. 
It stands to reason that it is extremely difficult to find a story that has 
been photographed that is so completely adaptable to toning as was 
this picture. The subject matter will decide whether other pictures 
will be similarly treated in the future. The mere application of a tone 
is not sufficient : a choice of the color resulting from the treatment is 
most important and vital for depicting the proper mood. 

A toned photographic image is quite distinct from a tint, in that a 
toned image consists of a color image embedded in a layer of colorless 
gelatin, so that while the highlights are clear, the shadows are colored. 
A tone may be applied chemically by the use of an inorganic metallic 
salt or by the use of a dye. It is, of course, most important that the 
toned photographic image be as transparent as possible for proper and 
adequate projection. In this respect some samples of toned film that 
appear fully toned upon hand examination produce a practically 
colorless effect upon projection. It is important, therefore, when 
judging a particular tone to view it upon a projection screen. 

A toning machine had to be designed and built for the work, using 
the general idea of a regular developing machine, rearranging the 
tanks, however, so as to be suitable for the process. The tanks were 
constructed of Allegheny steel and were set up in a lighted room, as a 
dark room was not necessary for the operation. For that reason the 
prints were not toned immediately after they were developed; they 
were dried first, and then put through the toning machine, air squee- 
gees being provided throughout the machine to prevent an excess 
carry-over of water, chemical, and dye. The machine operates at a 
rate of 90 to 100 feet per minute, depending upon the length of time 
required for the toning operation. The toning solution is a chemical 
one made up with uranium nitrate as the chief constituent. The 
formula used was that contained in the 1927 edition of "Tinting and 
Toning," published by the Eastman Kodak Company: 


Uranium Toning Formula T9 

Uranium Nitrate IG'A ounces 

Potassium Oxalate lOVa ounces 

Potassium Ferricyanide 6 x /2 ounces 

Ammonium Alum 2*/ 2 pounds 

Hydrochloric Acid (10%) 1 quart 

Water to make 50 gallons 

The chemicals were mixed in the order given in the formula. The 
temperature of the toning bath was approximately 70F. The time 
of toning was a variable, depending upon the depth of the tone de- 
sired, varying from 1 J /2 to S'/a minutes. It is important to remember 
that the effect of toning is to produce an intensification of the silver 
image and that the intensification increases with the time of toning. 
That means, of course, that the nature, or depth of the tone, changes 

The reaction of the toning bath is to replace the silver image in the 
positive film by uranium ferrocyanide. The film is placed in a single 
solution consisting of the metallic ferricyanide dissolved in a suitable 
solvent, such as the alkaline salt of oxalic acid in the presence of a 
mineral acid and certain other salts. The silver image is thereby 
partly converted to a mixture of silver ferrocyanide and the corre- 
sponding uranium ferrocyanide, thus producing a toned image. Fol- 
lowing the toning operation it was necessary to wash the film com- 
pletely so that all effects of the solution that are undesirable are re- 
moved. Highlights should be clear and the time of washing should 
be such as to render them clear. However, too long washing is det- 
rimental, in that some of the color will wash out, due to the fact that 
the uranium tone is soluble in water that is at all inclined to be alka- 
line. Normally a ten-minute wash is sufficient. 

The bath was made up in quantities of approximately 250 gallons, 
and as the film passed through it the solution was maintained at the 
desired strength by boosting at the rate of approximately two quarts 
of fresh, five times normal strength toning bath for every 2000 feet of 
positive film passed through it. 

The picture The Good Earth was approximately 12,000 feet long, 
consisting of 14 reels. There have been made from this negative ap- 
proximately 500 release prints, and all the prints have been toned. 

From the standpoint of sound, there is little to report other than the 
fact that the sound department advised that all tests made by them 
pertaining to the effect of toning the sound-track showed no detri- 
mental effects upon the quality of the sound. 



Summary. The design of a transmission-measuring system utilizing an Esterline 
Angus recording meter is described. A circuit was developed requiring a special 
triode exhibiting a logarithmic relation between change of grid bias and plate current. 
The audio oscillator is a commercial type to which has been added a synchronous 
motor drive geared to the frequency dial. For the amplifier -rectifier, required to oper- 
ate the 5-ma. recording meter, use is made of a push-pull class A amplifier terminated 
by a full-wave, approximately square-law tube rectifier, the d-c. output of the latter 
being connected to the recording meter. 

The paper concludes with a discussion of the various applications to which the sys- 
tem may be put. 

The need for a graphic record of transmission measurements has 
been recognized for many years, particularly in connection with the 
study of acoustical systems and other characteristics that play im- 
portant parts in the development, testing, and maintenance of electri- 
cal and acoustical apparatus. 

The technical literature describes numerous systems developed for 
this purpose, and many ingenious methods have been published, 
ranging from a simple, hand-operated stylus to elaborate photo- 
graphic registration. Logarithmic amplitude scales are most desir- 
able, and it will be well to mention briefly some of the more funda- 
mental methods used to obtain them. Ballantine used exponential 
tetrodes. 1 ' 8 Best describes a direct-current instrument with special 
pole-pieces. 2 Wente, Bedell, and Swartzel use an amplifier and rec- 
tifier, the gain being controlled by motor-driven potentiometers grad- 
uated in logarithmic steps, the gain settings of which are recorded. 3 
European methods differ from ours: Payne and Storey utilize the 
positive grid region of certain triodes. 4 Thilo and Bidlingmaier use 
the non-linear characteristic of copper-oxide rectifiers with tempera- 
ture control. 6 Peachey also uses the copper-oxide rectifier, but with- 
out temperature control. 6 Meyer provides a liquid potentiometer of 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. 
** General Service Studies, Inc., Hollywood, Calif. 




exponential shape. 7 More recently, several modifications of the origi- 
nal Ballantine method have been described. 9 ' 10>u 

A study of the various systems will indicate that a simple device 
that will provide a logarithmic amplitude scale is not at hand without 
resorting to a special tube and circuit, as described later. 

In designing our present equipment, the fundamental requirements 
we attempted to meet are as follows: 

(1) The equipment must be stable, rugged, simple in operation, 
and the recording portion must be portable and a-c. operated. 

(2) The response must be independent of frequency from 35 to 

FIG. 1. Experimental linear decibel scale amplifier. 

10,000 cps., 0.2 db., and effects of line-voltage change should re- 
main within these limits. 

(3) Effects of turn-over, wave-form errors, and stray magnetic 
fields at power supply frequencies must be reduced to a minimum. 

(4) A logarithmic amplitude scale that may be calibrated in deci- 
bels, and logarithmic change of oscillator output frequency are de- 

(5) Accurate marking of the completed record should be made in 
terms of the oscillator frequency dial calibration. 

The first three requirements have been met in a satisfactory manner, 
the fourth not at all, the fifth partially. 

Experiments with most of the generally known circuits, as well as 
several of our own, led us to believe it difficult to obtain a strictly 
linear decibel scale and at the same time provide the required degree 



[J. S. M. P. E. 

of stability, simplicity of operation, and freedom from line-voltage 
changes or tube replacements. 

The writer has developed a simple circuit (Fig. 1) which requires, 
however, that the tube manufacturers supply a special triode in which 
the plate current and grid bias follow the relation shown in Fig. 2, 
which is a strictly logarithmic relation between grid bias change and 
plate current. The usual variable-/* tubes do not follow this charac- 
teristic accurately, or over a sufficient range to be of much value. In 
Fig. 1, a class A push-pull amplifier terminates in a full- wave rectifier 


Negative Bias Voltage Ratio 

J L 

J L 

FIG. 2. 

Negative bias voltage ratio (Curves 1 and 2 show charac- 
teristics of 6D6 tube with different plate voltages) . 

made almost perfectly linear by reason of a large value of load resis- 
tance. The negative bias voltage produced as a result of signal rec- 
tification is applied to the grid of the logarithmic triode. A milli- 
ammeter in the plate circuit, and the recording meter with a variable 
shunt resistance in the cathode circuit, permit proper adjustment by 
means of the bias resistance, for full-scale deflection with reference 
signal input. Linear input signal increments will result in a logarith- 
mic reduction of plate current, obviously providing a linear decibel 
scale. The range in decibels is limited by the ability of the class A 
amplifier to supply signal voltage to the rectifier without overloading, 
and by the tube parameters chosen in designing the special tube. A 

July, 1937] 



range of thirty to forty decibels should be possible. An advantage 
possessed by this circuit arrangement is that excessive input signal 
will not damage the recording meter, since the plate current is re- 
duced to zero. 

Space limitations and lack of a suitable commercially available con- 
denser prevented adopting a logarithmic frequency change with re- 
spect to time. 1 ' 8 A mechanical cam arrangement is the most simple 

FIG. 3. Records obtained with the recording meter. 

solution of the problem, particularly if a variable condenser is used 
having a true "law" plate shape, such as a straight-line frequency 
type. 6 

We found that the simple method of engaging the oscillator dial- 
drive pinion at the beginning of the record is entirely satisfactory for 
use as a frequency fiducial in applying the transparent chart to the 
graphic record. This chart is marked in decibels and with frequencies 
corresponding to the oscillator dial calibration. (Fig. 3, showing also 

72 W. W. LINDSAY, JR. [J. S. M. p. E. 

the overall frequency response of the equipment as well as the 
effect of line voltage variation.) 

Theoretical requirements have been so well covered in the bibliog- 
raphy, that the remainder of this paper will be devoted to the prac- 
tical problems of mechanical and electrical nature encountered during 
construction of the apparatus. 

A commercial audio oscillator (Fig. 4) has been provided with a syn- 
chronous motor drive, connected to the frequency dial by means of a 
set of gears. A small, hand-operated lever permits engaging the gears 
so that the dial will begin rotating at the desired moment. The 
number of gears is so chosen that the graphic record starts at the 
high-frequency end of the scale. This is necessary with a left-hand 

FIG. 4. Audio oscillator, with synchronous motor. 

zero recording meter, otherwise the lower frequencies would appear 
upon the right, instead of upon the left-hand, side of the chart, as con- 
vention dictates. An additional pinion provides rotation in the op- 
posite direction when making "toe" frequency negatives. The speed 
of the motor and the gear ratios have been chosen to cover the fre- 
quency range in sixty seconds. 

A study of the circuit diagram (Fig. 5) will assist in following the 
description of details used to attain the desired results. 

The electrical circuits of the oscillator have been changed to provide, 
in conjunction with an external booster amplifier, constant output 
into 500 ohms, measured with a thermocouple instrument. The 
changes consist in removing a low-pass filter and adding a suitable 
output transformer and series capacity of the correct size to provide 
low-frequency equalization, as well as a series resistance which hap- 

July, 1937] 



pens to affect both low and high frequencies, in the right amount. 
The booster amplifier is normal, except that the input and output 
transformers have been changed to more recent designs. The result- 
ing output over the frequency range specified is well within the limits 

Having achieved a satisfactory oscillator-amplifier system, it re- 
mained to work out an amplifier-rectifier arrangement that would 
satisfactorily operate the five-milliampere recording meter. The 

Ci C2 


FIG. 5. Circuit diagram of the system. 

design chosen makes use of a push-pull class A amplifier, terminating 
with a full-wave, approximately square-law 12 tube rectifier, the d-c. 
output of the rectifier being connected to the recording meter. This 
provides an amplitude scale that is not linear in decibels, but is satis- 
factory from a stability standpoint. 

All the tube heaters are in series, and together with a small addi- 
tional resistance, are connected directly to the 110- volt supply. The 
B voltage required for the amplifier tubes is obtained from a voltage- 
doubling circuit, without the use of a high- voltage power transformer. 
The necessary filtering is obtained with capacity elements only. The 
input circuit is of the high-impedance type, and may be connected 



[J. S. M. p. E. 

FIG. 6. ( Upper) Amplifier-rectifier, with recording meter. 
FIG. 7. (Lower) Same, with covers removed. 


across a line having an impedance of 500 ohms in either direction 
without serious bridging loss (0.2 db. at 35 cps.; less at higher fre- 
quencies). The input circuit contains a series capacity and a shunt 
resistance which serve to maintain the low-frequency response. The 
input transformer feeds the signal to the two tube grids, and then 
after amplification by the tubes, is transformer-coupled to the full- 
wave rectifier. It so happened that this combination showed a 
slightly rising characteristic up to 12,000 cps. The addition of a 
small shunt capacity across the primary of the output transformer 
provides uniform response from 35 to 12,000 cps. 

Cathode resistor biasing was found to provide the required compen- 
sation for line- voltage fluctuations. A +10-db. signal at the input 
produces full-scale deflection of the meter. (Zero level equals six 
milliwatts in 500 ohms.) 

The full- wave rectifier is provided with a small adjustable resistance, 
which is set for the initial calibration and may be reset at a later date 
if necessary. In certain acoustic measurements, a large capacity 
across the meter acts as an integrating device, and serves to smooth 
out certain irregularities in the response curve, which are not of par- 
ticular interest. Care must be used, however, in choosing its value, 
since, if too large, it will give a false impression of flatness, and, also, 
it shifts downward the peaks and valleys in the frequency response 
curve. The value that we have found useful varies between 500 and 
2000 /if across a 570-ohm meter movement. With this capacity in 
the circuit, warble of the oscillator frequency is generally not used. 

This completes the details of the oscillator-amplifier and amplifier- 
rectifier recording meter combination. Fig. 6 shows the amplifier- 
rectifier in its case, with the recording meter beside it. Fig. 7 shows 
the same equipment with covers removed. 

Applications to which the equipment has been put are as follows: 

(1) Gain runs of all kinds, including amplifiers, microphones, loud 
speakers, light-valves, frequency films, and records, etc. 

(2} A recording microdensitometer has been achieved by using a 
modulated light-source, moving the sound-track past a scanning aper- 
ture at a slow, but uniform rate, and recording the amplified varia- 
tions due to density changes. 

(5) As a recording volume indicator, the instrument has been use- 
ful in studying recording and re-recording signal amplitudes. 

(4) The recording meter alone has been used for making direct 
current or voltage records of various transient phenomena. 

76 W. W. LINDSAY, JR. 

Other applications are too numerous to mention, and depend chiefly 
upon the problems at hand and the need for graphic record. The 
time saved is quite appreciable, and permits giving greater attention 
to other problems. The apparatus has been performing satisfac- 
torily since July, 1936. 

In conclusion, the author wishes to thank Mr. D. C. Hickson, Vice- 
President, and Mr. J. R. Whitney, Sound Director, of General Service 
Studios, Inc., for their cooperation in making this development pos- 
sible; and also to acknowledge gratefully the many helpful sugges- 
tions of his co-workers, Mr. J. G. Matthews and Mr. C. M. Ralph. 


1 BALLANTINE, S.: "Variable-mu Tetrodes in Logarithmic Recording," 
Electronics (Jan., 1931), No. 1, p. 472. 

2 BEST, F. H. : "A Recording Transmission Measuring System for Tele- 
phone Circuit Testing," Bell Sys. Tech. J. (Jan., 1933), No. 1, p. 22. 

3 WENTE, E. C., BEPDELL, E. H., AND SWARTZEL, K. D., JR.: "A High- 
Speed Level Recorder for Acoustic Measurements," J. Acous. Soc. Amer. (Jan., 
1935), No. 1, p. 121. 

4 PAYNE, E. L., AND STOREY, J. G.: "A Portable Program Meter," The 
Wireless Eng. & Exp. Wireless (Nov., 1935), No. 11, p. 588. 

5 THILO, H. G., AND BIDLINGMAIER, M. : "The Tone Meter," E. N. T. (May, 
1936), No. 5, p. 176. 

6 PEACHEY, F. A.: "Automatic Line-Level Recording Apparatus," Wireless 
Eng. (Sept., 1936), No. 9, p. 462. 

7 MEYER, E.: "Reverberation and Absorption of Sound," J. Acous. Soc. 
Amer. (Jan., 1937), No. 1, p. 155. 

8 BALLANTINE, S. : "A Logarithmic Recorder for Frequency Response Mea- 
surements at Audio Frequencies," /. Acous. Soc. Amer. (July, 1933), No. 7, p. 10. 

9 WHEELER, H. A., AND WHITMAN, V. E. : "Acoustic Testing of High-Fidelity 
Receivers," Proc. I. R. E. (June, 1935), No. 6, p. 610. 

10 HUNT, F. V.: "A Vacuum-Tube Voltmeter with Logarithmic Response," 
Rev. Sci. Instr. (Dec., 1933), No. 12, p. 672. 

11 TAYLOR, J. P.: "A D-C. Amplifier for Logarithmic Recording," Electronics 
(March, 1937), p. 24. 

11 WOLFF, I. : "Alternating- Current Measuring Instruments as Discrimina- 
tors Against Harmonics," Proc. I. R. E. (April, 1931), No. 4, p. 647. 




Summary. The studios occupy 28 acres of a 165-acre estate in Buckinghamshire 
about 17 miles from the center of London. Fine gardens stretching to the edge of 
dense woodland provide a natural setting that can be adapted easily for exterior pho- 
tography. There are seven stages, totalling 120,000 square-feet of floor area. Two 
stages are 250 by 120 by 45 feet (high) ; two are 125 by 120 by 45; and three are 120 
by 80 by 35. Details of the foundation and wall construction are given. The main 
reviewing theater is designed for reviews and for scoring; for the latter the reverbera- 
tion period can be adjusted to 0.8 second and for the former, 1.5 seconds. 

A description is included of the various shops that service the studios, not only 
for set construction but also for equipment. The metal shop, for example, has turned 
out more than 700 lamps for set lighting, two optical printers, a projection printer, a 
stop-motion machine, and a rear projector. 

In the sound stages, only the dubbing channel is of the permanent type. A brief 
description is given of the portable sound channels, the camera department, and the 
processing laboratories. Two automatic developing machines, capable of developing 
480 and 1000 feet per hour, are available for film processing. Automatic mixing 
equipment is used for preparation of solutions. 

The electrical power plant is described and details are included on fire protection, 
water supply, and sewage disposal. 

It is important that a British studio be situated in close proximity 
to good natural settings so that production hold-ups may be reduced 
to a minimum by the use of alternative exterior and interior schedules 
for fine or wet weather. London Film Productions' studios are hap- 
pily situated in this respect in that the estate, though only some seven- 
teen miles from the center of London, is in the heart of Buckingham- 
shire's reputedly fine scenery. 

The estate itself is 165 acres in area, of which the studio occupies 
28 acres. The River Colne winds through the estate for l l /^ miles, 
and widens out into a lake by the lawns of the Old House, formerly 
the residence on the Denham Estate. There are fine gardens stretch- 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
April 19, 1937. 

** London Film Productions, Ltd., Denham, Middlesex, England. 




[J. S. M. P. E. 

ing to the edge of dense woodland possessing a surprising variety of 
trees, while the upper reaches of the river run through typical English 

It is there that many permanent sets have been constructed in a 
setting that can be easily adapted for exteriors of almost every kind. 
The site is naturally insulated against sound, for the only chance of 
noise on one side a country road is effectively screened by trees in 
most parts, while on the other the country is entirely devoid of build- 
ing development. The possibility of the spoiling of the sky-line is 
remote, for large areas of the surrounding country and part of the 

FIG. 1. General layout of the studios. 

estate are included in a town-planned green belt upon which building 
can not take place for at least twenty years. 

The value of such locations, literally at the back door of the studio, 
can not be gainsaid. Production units remain under executive super- 
vision, and also have the advantage of the studio power supply, stores, 
accommodation, and catering arrangements. 

Such was the setting chosen by Mr. Korda for the construction of 
a studio at least as modern, it is hoped, as any in the world. It was 
commenced with the initial advantage that it was to be built as one 
complete whole, and all possibilities of future development for many 
years to come laid out in the original plans. 

The tremendous amount of thought arid knowledge put by Mr. 
Jack Okey into the scheme can only now be fully appreciated, for the 
studio was built at a time when contractors and specialists in this 


country had little experience with plants of such size, with their 
trains of pitfalls. All the pitfalls had to be watched for and avoided, 
and a scheme evolved that was to house a complete community ca- 
pable of making sound and color-films upon a large scale. Everything 
possible was to be produced on the premises, with a minimum of calls 
upon outside resources, from power supply to the processing of the 
exposed film. 

Fig. 1 shows the general layout of the studio. The main entrance 
and gatehouse are at the top left-hand corner, and the garage just 
below. There are three entrances to the front block of buildings, 

FIG. 2. Front view of stages. 

south, central, and north. The administration offices are grouped 
near the south entrance, together with the sound department, main 
review, and scoring theater. The executive offices are situated on the 
first floor overlooking the main entrance and the surrounding coun- 
tryside. The central entrance is, in effect, a private entrance giving 
access to an individual two-story block of offices for the use of renting 

Dressing rooms, make-up, wardrobe departments, and casting 
offices are grouped near the north entrance, where crowds are checked 
in and paid off. Beyond is the studio restaurant. The whole of this 
front block is interconnected with corridors and glass-covered ways 
that feed into a main transverse corridor connecting the stages the 
hub of all film studios. Covered ways are a very necessary feature. 
Apart from access to the shops, there is little need for anyone to go 

80 L. C. FERMAUD [J. S. M. P. E. 

into the open air, where costumes may be damaged by rain or one may 
catch cold by the sudden changes of temperature in the winter time. 

At the base of stages 4, 5, and 7 are three two-story annexes, 
housing, respectively, the special-effects department, art department, 
and the still and camera departments. 

The power station will be seen placed centrally, immediately below 
the stages with the two stage air-conditioning fan chambers, and the 
boiler house adjoining. This position for the power station was 
chosen in order to reduce to a minimum the length of the bus-bars to 
the stages, with the resultant saving in cost and minimizing of the 

FIG. 3. Rear view of large stages. 

voltage drop. The workshops are housed in three buildings to the 
south of the stages, the various departments being arranged as far as 
possible in the order of the procedure of work. 

Owing to the large area that a number of sound stages must cover, 
even when grouped as closely as practicable, and the consequent long 
distances to be traversed, it was considered most satisfactory to ar- 
range the shops together in one group for easy intercommunication, 
and to feed their output to the stages in low-loading lorries. 

With the exception of the road leading down from the main en- 
trance, which is thirty feet wide, all roads are twenty-five feet wide 
with five-foot grass verges on each side, giving a standard distance 
between buildings of thirty-five feet. Though it has proved difficult 


to persuade the grass to keep on growing, the green verges add greatly 
to the impression of airiness about the studio. Fig. 2 shows the front 
elevation from the dressing room end, and Fig. 3 the rear of the large 
stages with their annexes and air-conditioning extract turrets. 

All buildings are steel framed. A total of 4500 tons was used. 
There are over 700 tons of steel in each of the three large stage build- 
ings. Apart from the shops, where the walls are covered with asbes- 
tos sheeting, and stages 1, 2, and 3, where they are of brick, walls are 
of 4-inch reinforced concrete. The low-pitched roofs of the front 
block, which are concealed by parapet walls, are of roofing felt laid 
upon close boarding on wood purlins. The remainder of the 25- 

FIG. 4. General view of studios from the air. 

degree pitched roofs of the stages, power station, shops, etc., are of 
green-colored asbestos cement, "Watford" tiles. These green roofs, 
which blend with the natural green of the countryside, were decided 
upon after cooperation with the local town-planning authorities, who 
were as anxious as the Company that the studio should not spoil the 
amenities of the district by striking a contrasting note. 

The broad, square corrugations of the gray asbestos cement sheets 
used on the shops is a great improvement on the more usual 3-inch 
corrugated material. Moreover, it is not so liable to breakage. If 
breakage does occur, individual sheets can be quickly and inexpen- 
sively replaced without disturbing the rest of the wall. 

It was decided to build stages 1, 2, and 3 only after the major part 
of the studio was completed. The stages were required urgently, 



[J. S. M. P. E. 

and are consequently made of brick, for brick is the British work- 
men's favorite type of construction, and at which he is quickest. The 
tie-beams between the stanchions were laid upon their sides, and the 
4 1 / 2 -mch brick panels built upon the webs for stability. The exposed 
flanges were afterward wire-lathed and the exterior rendered in 

The entrance halls, principal offices, and stars' dressing rooms are 
finished in plaster. The remainder of the offices and dressing rooms 

FIG. 5. Sound stages under construction. 

are papered on wallboard on stud partitions. This type of construc- 
tion, apart from being cheap, possesses the advantage that partitions 
may be removed, or new doors cut, very easily and without the need 
for complete redecoration. 

Fig. 4 is a general view of the studio from the air the workshops 
upon the right, the semicircular end of the main review and scoring 
theater just inside the main entrance, and the laboratories, where the 
film is processed, on the extreme left. 

Fig. 5 shows the sound stages during the course of construction. 
Each of the roof trusses, which are composed mainly of double chan- 

July, 1937] 



nels, weighs twelve tons, and is designed to carry a load of two hun- 
dred pounds per foot run of truss. Interlocking steel shuttering was 
used for the concrete work, the walls being raised uniformly by pour- 
ing a four-foot ring of concrete every day, except, of course, when 
heavy frost caused a hold-up. 

The framing to the stage walls is seen in Fig. 6. The double 
stanchions at the lower part of the wall were required in order to keep 
air-conditioning input ducts within the thickness of the wall without 
encroaching upon the floor space. These ducts branch off the main 
duct, the trench for which is at the base of the wall. 

FIG. 6. Interior of large stage. 

The seven stages total 120,000 square-feet of floor area. There are 
two each, 250 X 120 X 45 feet high, two 125 X 120 X 45 feet high, 
and three 120 X 80 X 35 feet high. The two 125 X 120-foot stages 
are in reality one stage identical to the two large stages, but with a 
sound-proof dividing partition across the center. 

The floors of all stages are composed of 1-inch G & T boarding, 
secret-nailed to 1-inch close boarding. Water-proof paper was laid 
between the boardings to prevent squeaking. There is an ample num- 
ber of electricians' runways in the roof trusses to facilitate lighting. 
The stages are also equipped with tracks and chain tackle. All doors, 
including those of the shops, are of standard size, 20 feet high by 16 
feet wide, so that anything that can be got out of the shops can also 
enter the stages, and vice versa. 

84 L. C. FERMAUD [J. S. M. p. 

Particular attention was given to the design of the sound-proofing 
and acoustic treatment, particularly in the case of the bigger stages, 
where it was thought that the large area of the comparatively thin 
walls would tend to transmit sound by resonance. It was conse- 
quently thought necessary to form an inner shell for both walls and 
roof with a dead air space between it and the structure, the shell to be 
isolated from the main structure as far as possible so as to prevent the 
passage of sound by vibration. 

The treatment decided upon for the walls consists of a 6 X 2-inch 
wood frame spaced about iy 2 feet from the outer wall. This is tied 
to steel channels fixed to the inner face of the main stanchions by 
bolts insulated from the steel frame by cork sleeves and washers. 
Two-inch sheets of woodrock, a material consisting of wood shavings 
cemented together, were nailed to the wood frame, then 1 /2-inch 
plaster board, and finally rock-wool blankets. The inner shell of the 
roof is of similar construction. It is secured to a second row of pur- 
lins hung from the main purlins by steel straps and insulated from 
them by cork seatings. The actual asbestos roof was laid directly 
upon two layers of woodrock. The sliding doors are all double, the 
outer one hung from the steel frame, and the inner from the sound- 
proof shell. They are structurally separate, and are 4 inches thick, 
composed of two outer layers of 1-inch G & T boarding, the inter- 
vening space being composed of celotex sheets. Splayed felt and 
rubber buffers prevent the passage of sound at the edges. 

The dividing partition between stages 6 and 7 presented a special 
problem, particularly since doors were required between the two 
stages. A system similar to that employed for the external walls 
was followed. Two wood-framed partitions were secured by cork- 
insulated bolts on each side of a supporting steel frame upon separate 
foundations. The doors in this case were hinged, to provide a better 
seal, and are entirely independent of each other. 

The sound-proofing of the stages proved very efficient. As a test, 
the noise of an aeroplane flying 500 feet directly overhead was not 
sufficient to have prevented shooting. Production can also be con- 
tinued in stages 6 or 7 while sets are being erected in the other, the 
dividing partition satisfactorily baffling the sound. 

Another acoustic problem, the only one of its kind in this country, 
is the main review theater. In order to -avoid a duplication of thea- 
ters, it was necessary that it should not only have a suitable rever- 
beration period, and good appearance for important reviews, but 


should also possess a variable reverberation range for scoring and 
dubbing. The range required was from 0.8 second for scoring and 
dubbing to 1.5 seconds for review, which is obtained by a number of 
reversible hinged panels upon the side walls. These panels are 4 
feet wide X 28 high, and are constructed of wood upon a steel frame 
tied to a tubular steel rod at the hinged side to prevent whipping. 
One side is covered with 3 / 8 -inch plywood painted to conform to the 
general color scheme, and the other is padded with rock-wool. In 
spite of their weight, the lightness of their bearings renders it a simple 
matter to reverse them. Large sliding doors can be pulled across the 
front of the screen to form a sound-reflecting background for an 

The two shop buildings running parallel to the stages are 272 feet 
long (the same length as the stages plus their annexes) by 80 feet 
wide. They house, in one, the modellers, plaster, paint and pattern 
shops, and the grips storage; and, in the other, the electrical equip- 
ment and property storage, and the papier mache and drapery shops. 
The third shop building contains the general stores, carpenters' 
shop, mill, timber racks, metal shop, foundry, and blacksmith. 
These buildings are specially well lighted by side windows and broad 
roof lights. The interiors are distempered white, the doors, offices, 
etc., being painted a pale gray. 

The carpenters' shop is 192 X 120 feet in area, which provides 
ample space for the laying out and constructing sets under cover. 
The mill adjoining contains all the heavy machinery. Timber is 
drawn in bulk from the racks, which open directly into the mill, for 
cutting on the self-feed circular saw. These two shops are fully 
equipped with the most up-to-date machinery available, including 
tenoning and mortising machines, spindles, band-saws that cut to any 
radius, a lathe, self-feed planing machines that will take material up 
to 26 inches wide, and a jointing machine. Two portable circular 
saws are also available for bench use. 

The metal shop is, without question, the finest of its kind in Europe. 
With the assistance of the pattern shop in preparing the wood pat- 
terns for the moulds, there is practically nothing that it can not pro- 
duce. Apart from normal production work and equipment main- 
tenance, more than 700 lamps for set lighting, two optical printers, a 
projection printer, stop-motion machine, and a rear projector, have 
been turned out, practically in their entirety. 

The shop is equipped with power hammers, hacksaws, and planing 


machines, nine lathes from 4 x /2 to 9 inches, a shaper, a radial drilling 
machine, tool grinders and cutter grinders, a fully universal milling 
machine with attachments for gear cutting, an electric spot welder, 
and two oxyacetyline welding plants. There are also bending ma- 
chines, guillotines, rollers, and presses for the sheet-metal workers. 
Opening off one side of this shop are the foundry and blacksmith's 
shop equipped with three foundry furnaces for 60 to 120-pound pots, 
and a forge. Camera repairs are carried out in a small specially 
equipped shop in one corner of the metal shop proper. 

Owing to the relatively high cost of timber, some 75 per cent 
greater than in Hollywood, a considerably greater amount of plaster 
work is done in the plaster shop than is done in the American studios. 
Twenty- or thirty-foot columns that might otherwise be of wood are 
molded more economically in plaster. The shop is 80 feet square. 
During production peaks, more than 200 men have used 42 tons of 
plaster in a week. Considerable quantities of plaster work are 
stored in a separate building outside the doors of the plaster shop. 

The next shop in this block is the painters,' which includes a 
mechanically ventilated spray room, a sign writers' room, and a 
finishing shop. Then there is the pattern shop, 64 X 80 feet, 
equipped with its own machinery, and the grips, which includes the 
camera equipment store, and special-effects model store. 

Each of the two floors of the property store are 144 X 80 feet in 
area, and include a separate store equipped with cupboards, racks, 
unpacking tables, etc., for small properties. Most properties that are 
not normally kept in the studio can be obtained in London, although 
not from one particular source. Many large shops specialize in a 
single type or period of furniture, such as Queen Anne, Louis XV and 
XVI, or modern sycamore. Consequently, much depends upon the 
experience of the property buyers in knowing where to look for their 

The electrical repair shop and store look after all electrical floor 
equipment, as distinct from electrical supply. It possesses nearly 
1000 lamps from 1000-mm., high-intensity arcs to the smallest photo- 
floods, seven portable generators for location work with capacities up 
to 1000 amperes, and more than 30,000 feet of cable. Mention must 
also be made of the six electrical wind machines, two lightning ma- 
chines, and the rain effects. Most of this equipment was made in the 
studio shops. 

The drapery shop follows normal procedure. It contains the usual 

July, 1937] 



racks, benches, and sewing machines, and .facilities for stencilling. 
A well on one side of the shop enables large quantities of drapes to be 
stored, up to a length of about 30 feet. 

Fig. 7 shows the internal planning of the front block in more detail. 
There are 56 dressing rooms, 16 for stars and 40 for small-part 
players. Each star's room has a bathroom adjoining, and four of 
them have private sitting rooms. With the exception of the chairs, 
all the furniture was designed and made on the premises. Dressing 
table and table tops are covered with sheet aluminum, which looks 
attractive, does not crack, can be easily cleaned, and is fire proof . 
The two "crowd rooms," each capable of accommodating 500 extras 
are equipped with steel lockers, and showers in a separate room. 

The wardrobe department, on the opposite side of the corridor 
from the make-up department, covers an area of 102 X 57 feet, and 

FIG. 7. Plan of the front block. 

contains the wardrobe room proper, a large workroom and store- 
room, two fitting rooms for men and women, costume designers' 
rooms, and offices. Ten thousand costumes have been handled with 

The sound installation comprises equipment to cover the needs of 
the seven stages, two review theaters, and the large combined review, 
scoring, and dubbing theater. To assure maximum flexibility, only 
the dubbing channel is of the permanent type. Permanent wiring 
between the stages and "Bay X," a central control panel enables 
portable channels to be used from recording rooms to serve any two 
stages, other stages being served by recording trucks. By this means, 
the problem of location work is simplified, as a minimum of time is 
required to get a unit ready for changing over. Since it is imperative 
to construct cover sets owing to climatic conditions, flexibility is of 
paramount importance in equipping an English studio. 

88 L. C. FERMAUD [J. S. M. P. 

For foreign location work, the type F channel still remains tl 
most satisfactory, since in its compact units it can be carried ovt 
ground that would be impassable to a loaded truck. The FB chan- 
nel, though not so compact, can not be bettered from the point 
view of reliability. It is a testimonial to the consistency and excel- 
lence of the product that for us the latter is the accepted standard 
quality. The new QB channel at first presented some difficulty 
owing to its extended frequency range, and coupling with that the 
use of the new 630 microphone, it was found necessary to review mi- 
crophone technic to meet the new conditions. Disk recording ge 
is available for all stages. There are also two type F, two FB, and 
three QB channels. 

Power supply is obtained from an independent power room in the 
basement below the sound department, where the studio d-c. supply 
is converted into the various a-c. and d-c. voltages required by the 
sound equipment. There is also a film processing room where a check 
is kept upon the behavior of the developing and printing laboratories, 
and the test-room where everything comes to pieces sooner or later. 

The camera department possesses its own offices, darkrooms, test- 
rooms, and storerooms. To avoid the risk of fire, all camera equip- 
ment is kept in fire-resistant steel lockers, and only the days' supply 
of negative film is brought from the vaults to the test-room. The 
equipment includes eighteen cameras, including eight super-Parvo 
Debries, four N. C. model Mitchells, and three Newman Sinclair, 
four Fearless Panorama Velocilators, an electric velocilator, and a 
camera crane. Eleven units have been serviced satisfactorily at one 

The still department is equipped for all types of work publicity, 
fashion, portraits, and color photography. It is at present capable 
of producing 1000 prints a day, but room has been allowed for expan- 
sion. There is one Kodak auto-focus enlarger, two miniature en- 
largers, two Kodak printing machines, and the usual print develop- 
ing and washing facilities. All development is carried out in rooms 
at standard temperature by tank at fixed time and temperature. The 
negative drying room is also of standard temperature, with a con- 
stantly circulating current of air passing through it. Each negative 
dries in 40 minutes in a controllable temperature, to prevent the 
emulsions from becoming brittle; 750 10 X 8-inch negatives can be 
dried per day. A portrait studio with two dressing rooms is incor- 
porated in the department, in which facilities are available to enable 


sets to be introduced so that stills may be in -keeping with stage pro- 

Trick work, up to recently, has not been used so widely in England 
as in America. In view of the type of their productions, however, the 
Company has gone to considerable pains to provide itself with a 
thoroughly equipped special-effects department. It is self-contained, 
with its own developing, printing, cutting, camera, and darkrooms, 
projection theater and insert room. A large concrete tank has also 
been constructed in the grounds for trick work. It is 150 X 120 feet 
in size with a 40-ft. high steel framed backing along one side, and a 
30,000-gallon dump tank with a 30-ft. head of water nearby. 

As has been stated, much of the special-effects equipment has been 
designed and made in the studio. This has been necessary since ma- 
chines with the necessary range of operations could not be obtained. 
The major items of equipment include two rear-projection machines 
with Bell & Howell camera movements, which give perfect registra- 
tion and assure a steady picture on the screen. These machines are 
equipped with Brenkert high-intensity arc lamps. There are also a 
stereopticon projection machine with which a slide can be held upon 
the screen for as long as iy 2 hours, without danger of damage to the 
slide from heat, and an ice-cooled fog machine capable of laying a fog 
non-injurious to health. 

In the optical printing room, are a projection printer and two op- 
tical printers. The former has an adjustable screen with clips for 
holding sheets of glass so that the operator can project pictures upon 
the screen and take out any part of the picture being projected, and 
then photograph with a Michell camera mounted on the other end of 
the bed. The optical printers are equipped with standard Bell & 
Howell camera movements. 

There is also a contact printer which is used to make blue-prints 
for the optical printer as well as rear projection prints. The light is 
brought in contact with the film through a lens with a number of 
ground glasses between the light and the lens in order to obtain an 
even field of light. By the use of various glasses having darkened 
centers, "hot-spots" on the projection screen can be eliminated. 
This printer was designed because a contact print is sharper and 
steadier than an optical print, and can be made at much lower cost. 
There is also a standard Bell & Howell continuous printer for daily 
rushes as well as for projection prints that are moving. 

In the laboratory are two automatic developing machines, capable 

90 L. C. FERMAUD [j. s. M. P. E. 

of turning out between 480 and 1000 feet of film per hour. The time 
of developing can be changed while working, without stopping the 
machine. Each machine has its own refrigerating plant, heating 
system, and pumps for circulating the solutions. The laboratory is 
also equipped with an automatic mixing machine for mixing the 
chemicals, and water filters and softeners. 

The cutting department, with its 14 cutting rooms and film vaults, 
is situated near the Old House. They are equipped with Moviolas 
and the usual modern cutters' equipment. Most of these cutting 
rooms were brick built stables, converted for the sake of economy. 
The music department is nearby. It is an old cottage modernized, 
and is away from the noise of the studio proper. 

Many factors required careful consideration before a decision could 
be made on the system of power supply. Steam turbines, Diesel 
engines, and a supply from the public companies were all considered. 
The steam plant was ruled out, due to the possibility that the dirt 
arising from the coal boilers would affect the air-conditioning of the 
stages. Supply from a public company would have been very con- 
venient, but the cost of acquiring such a supply and converting it to 
direct current made this course prohibitive. Apart from these rea- 
sons, the Diesel-electric system was chosen because capital charges 
were in its favor, and the possibility of "black-outs" due to interrup- 
tion in the supply were at a minimum compared with other systems. 

The plant consists of six Crossley- Premier oil engines, each directly 
connected to a Mather & Platt three-wire static balanced generator, 
each of 750-killowatt capacity, giving a total output of 4500 kilo- 
watts. The power station was designed to take two further sets, 
making a total of eight to allow for the increased demand when future 
stages are constructed. The generators are designed to supply 230/- 
250 volts across the outers of the three wires. Overload capacity is 
25 per cent for two hours, obtained by supercharging the engines. 

Fig. 8 shows four of these generator sets. They are mounted on 
heavy concrete bases some seven feet deep, which in turn rest upon 
the foundations. Between these two masses of concrete is a three- 
inch mat of cork to eliminate vibration. The bus-bars and cables 
are in the alleyways formed between the bases below the general floor 

On the control desk six sets of push-button panels control the gen- 
erators. On the front of the desk are the field regulators and switches, 
the regulators themselves being operated and mounted in the base- 


ment below the control room. A Chadbufn electric telegraph en- 
ables the control engineer to signal for any machine to be started or 
stopped; in addition he has an excellent view of the engine room 
through the window at the back of the desk. 

Fig. 9 shows the switchboards at the sides of the control desk de- 
voted to the smaller feeders. The main studio circuits are controlled 
by hand-operated circuit-breakers in the basement, from which the 
bus-bars run on the roofs of the ventilating ducts to the distribution 

FIG. 8. Four of the six 750-kw. generators in the power plant. 

panels at stage-floor level, and also to the catwalks from which the 
overhead lights are controlled. The power for the workshops 
is supplied by two motor-alternators of 220-kva. capacity at 400 
volts. Fuel for the Diesel engines is stored in a 50-ton tank in the 
open air, adjoining the power station. It is enclosed on all sides by a 
concrete wall. 

Starting air is stored in two cylinders at 250 Ibs. per square-inch, 
and is normally supplied by a motor-driven compressor. Due to the 
importance of reliability, the compressed-air storage capacity was 
made sufficient to enable each engine to make six starts from cold, a 



|J. S. M. P. E. 

total of forty-eight starts, before recharging is necessary. In the 
event of the station's being put out of commission, and the charge 
in the cylinders becoming lost, air can be compressed by a small inde- 
pendent hand-started Diesel engine. An individual Ingersoll-Rand, 
Mather & Platt, motor-driven service compressor, situated in the 
power station, supplies compressed air to numerous points in the 
stages, shops, etc. 


FIG. 9. Feeder circuit switchboard. 

The water services presented a special problem. The service had 
to cover not only the domestic and hot water supply for the offices 
and dressing rooms, but the supply for the air-conditioning plant, 
stage heating, and engine cooling. In view of the tremendous quan- 
tity required, the cost of a supply from the local water company 
mains would have proved exorbitant. 

To obtain a supply for engine cooling was comparatively simple, 
since the river passes within a hundred yards of the power station. 
The water is pumped from it to tanks situated on the power station 


roof. The remainder of the supply is obtained from an artesian well 
bored to a depth of 320 feet. The water is pumped at the rate of 
10,000 gallons an hour to a reinforced concrete water tower concealed 
in the woods. From the tower, a network of mains runs to the various 
parts of the studio, and to a number of local supply tanks. 

The heating of the studio is divided into four systems operated 
from three individual sources of supply. These are, briefly, air-con- 
ditioning to the four larger stages; low-pressure hot water for the 
three smaller stages and annexes; gas-hot-air radiators for the work- 
shops; and low-pressure hot water again for the front block. 

Owing to the considerable length of pipe runs that would otherwise 
be required, it was considered necessary to install an independent oil- 
fed boiler plant for the front block heating. The other boiler plant 
adjoining the power station, and which can virtually take its supply 
of heat under heavy load conditions from waste-heat boilers in the 
power station, feeds the air-conditioning plant and the smaller stage 
and annex heating. 

The studio also possesses its own sewage disposal plant, which was 
necessary owing to the absence of a public sewer in reasonable proxi- 
mity to the studios. The sewage gravitates to collection tanks from 
which it is pumped through a rising main to the disposal plant at the 
far end of the estate. 

The major part of the studio is protected from fire by a sprinkler 
system. The whole of the workshops, stages, offices, etc., can be 
covered by means of fire hose connected to a large number of stand- 
pipes around the site. 

Last, there is the estate department, which, apart from cultivat- 
ing shrubs and flowers, and tropical plants in the seven glass-houses, 
endeavors to keep the estate tidy in spite of the fact that a set always 
is built exactly where they have just finished some planting. 

The writer is indebted to Mr. Watkins of the sound department, 
Mr. Denham, the engineer, Mr. Mann and Mr. Woods of the special- 
effects and still departments, respectively, and to others of Mr. 
Alexander Korda's organization for their assistance in supplying 
the information concerning their departments and equipment. 


During the Conventions of the Society, symposiums on new motion picture appara- 
tus are held, in which various manufacturers of equipment describe and demonstrate 
their new products and developments. Some of this equipment is described in the 
following pages; the remainder will be published in subsequent issues of the Journal. 

J. FRANK, JR.** 

During the nine years since the introduction of sound reproducing equipment, 
the motion picture industry has witnessed the development of more heavily con- 
structed devices, often of considerable weight, such as modern sound reproducers 
with directly connected motors in front, heavy-duty arc lamps, more sturdily 
designed projector mechanisms, and larger magazines. The weight of all this 
apparatus is far in excess of that for which the earlier pedestals and stands support- 
ing all these units were designed. More recently the introduction of the standard 
2000-ft. release print has placed a further burden of weight upon motion picture 
projection and sound reproducing equipment. To meet these demands, the 
International Projector Corporation has placed upon the market a new supporting 

The new Super Simplex pedestal is extremely symmetrical, harmonious in de- 
sign, and provides an excellent balance for the heavy-duty equipment it must 
support. It has also been designed to permit all the necessary quick adjustments 
greatly desired and appreciated by projectionists. 

Previous pedestals were designed for the old type silent projection equipment 
using slide-over attachments for the projection of stereopticon slides. This made 
the pedestal somewhat flimsy; but nevertheless it adequately supported the 
equipment that was mounted upon it. Modern equipment mounted upon such a 
pedestal is not properly balanced due to the location of the pivot point. Further- 
more, the great weight of the equipment places a burden upon the old pedestals 
that almost reaches the danger point. The new Super Simplex pedestal ade- 
quately meets the requirements. The pivot point has been moved back under the 
lamp house table, resulting in excellent balance, and requiring only the slightest 
exertion to raise, lower, or horizontally adjust the entire apparatus, so that at an 
instant's notice it may be accommodated to the screen position. 

Two convenient adjustments are provided, one for tilting, and the other for 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received 
April 1, 1937. 

** International Projector Corp., New York, N. Y. 



lateral displacement. The former adjustment has a unique feature eliminating 
the necessity for a long lead-screw. Three positions for the horizontal rod sus- 
pension have been provided. This permits the use of a short lead-screw for tilting. 
With the rod in the top position the pedestal is locked into position at the maxi- 
mum angle of tilt by the control. Then the thumb-screw on the horizontal rod 
is loosened and the rod easily removed. The lead-screw is then adjusted so that 
the horizontal rod may be properly placed in the center position. The pedestal 
may then be further tilted. By repeating this operation and placing the horizon- 
tal rod in the lower position, angles of tilt from minus 3 to plus 33 may be easily 

FIG. 1. Super Simplex pedestal and RCA 
Photophone rotary stabilizer sound head (oper- 
ating side). 

accomplished. The lateral adjustment, accessible from either side of the pedestal, 
permits a horizontal angle of approximately 3Vz degrees about the pivot point 
located in the rear of the pedestal. Four knobs are turned to lock the pedestal in 
its horizontal position. When the pedestal is installed and the adjustments finally 
locked in place, the entire assembly is rigidly mounted, and the absence of vibra- 
tion, due to the great weight of the whole unit, gives a steadiness to the entire 
equipment heretofore unobtainable. 

The pedestal is provided with a spacious internal compartment into which may 
be brought all electrical connections, thus eliminating the network of wires and 
cables distributed around the projector in an unsightly manner. Where it is not 
convenient to bring up the conduits through the floor in the proper position, they 
may be brought into the compartment through a plate especially provided in the 


non-operating side. If this is not necessary, this plate provides a suitable location 
for a fuse-box, if desired. 

Two flush twist-lock receptacles are located on the non-operating side, one a 
three-pole for the change-over device, and the other a two-pole for the operating 
motor. This allows for readily disconnecting either of these important circuits 
without the necessity of breaking soldered joints, when the occasion arises for 
making a quick change of equipment. 

Two 3-way, 30-ampere switches, one on either side of the pedestal, are 
mounted upon the pedestal for the operating motor circuit, so that the motor may 

FIG. 2. Super Simplex pedestal and ERPI 
heavy-duty Mirrophonic reproducer (operating 

be readily controlled from either side of the equipment. A further improvement 
is provided through a number of double-pole standard outlet receptacles into 
which may be plugged soldering iron, work light, threading lamp, or other auxil- 
iary equipment. The arc lamp feed-motor also may be connected to one of these 
to provide an instant means of disconnecting this unit when necessary. 

A universal type spirit level forms part of the unit, so that the equipment may 
be accurately levelled in the projection room when installation is made. The 
base of the pedestal is provided with levelling bolts fitted into solid steel cupped 
flanges, so that the stand may be levelled at all corners and still give excellent 
rigidity regardless of the unevenness of the surface upon which it stands. 

The lamp house support bracket is of entirely new and unique design. It is of 
much more ample dimensions than any heretofore constructed, so that its length 

July, 1937] 



adequately supports the much longer lamp house structure than was possible on 
any pedestal previously designed. For the first time it is possible with this unit to 
align accurately any type of standard lamp house regardless of slight errors that 
may exist in manufacture, so that the positive carbon axis is in accurate alignment 
through the optical system. The bracket may be tilted upward or downward at 
either end, from side to side, and raised or lowered vertically as a complete unit. 
This is accomplished by providing holes for the mounting screws twice as large as 
the screws, permitting displacement in all directions. A screw at the rear posi- 

FIG. 3. Diagram of pedestal, showing adjustments. 

lively controls the vertical adjustment at the rear. Large washers and nuts per- 
mit positive fastening of the screws in any desired positions in the large holes. 
Absolute rigidity is obtained by tightening the four nuts involved. 

When lamps of the low-intensity or high-intensity Suprex arc type are used, a 
100-ampere, double-pole knife-switch is provided, mounted in a heavy cast-iron 
switch-box attached to the pedestal. Where straight high-intensity arc equip- 
ment is used a heavy switch-supporting bracket attached to and supported by the 
rear lower pedestal section is furnished, and it is recommended that a heavy-duty, 
200-ampere switch and switch-box such as the "Square D" be used. The heavy- 
duty switch-supporting bracket is sold at a slight additional cost. Three holes 



with insulators are located in the rear of the pedestal through which the asbestos 
wires for the arc lamp supply may be run. 

A flat surface is located on the front operating corner of the pedestal, to which a 
standard change-over may be attached. 

Since the sound reproducers of various manufacturers are not standardized in 
design, it is not possible with a pedestal of unit design to conform to all existing 
projection port-hole constructions because the relative position of the mechanism 
to the pivot point varies as much as 8 inches, depending upon the sound reproducer 
employed. Spacers, therefore, are furnished in 1-, 2-, 3-, 4-, 6-, and 8-inch sizes to fit 
between the lower and upper pedestal sections to fit the existing port -hole location. 

For the same reason a number of different sound reproducer support-arms are 
available. The proper support-arm for the sound reproducer to be installed is 
furnished as part of the pedestal. With some types of sound reproducers it is 
necessary, for angles greater than 20 degrees, to provide a special support-arm to 
avoid interference between the pedestal front and the rear of the lower magazine. 

The new Super Simplex pedestal will accommodate the Simplex sound projec- 
tor, Type 5.4, in which case the lamp house bracket is eliminated. The 100- 
ampere arc lamp switch is furnished for this equipment. 



The editors present for convenient reference a list of articles dealing with subjects 
cognate to motion picture engineering published in a number of selected journals. 
Photostatic copies may be obtained from the Library of Congress, Washington, D. C., 
or from the New York Public Library, New York, N. Y. Micro copies of articles 
in those magazines that are available may be obtained from the Library of the U. S. 
Department of Agriculture, Washington, D. C. 

Academy of Motion Picture Arts and Sciences, Techni- 
cal Bulletin 

(March 31, 1937) 

Specifications Standard Electrical Characteristics for 
Two-Way Reproducing Systems in Theaters (p. 3). 

American Cinematographer 

18 (April, 1937), No. 4 
Dodd Describes B-M's New Type 24-Inch Sunspot 

(p. 134). L. E. DODD 

Mitchell Announces New Sound Recorder (p. 138). 
Art Reeves Introduces All-Purpose Developer (pp. 

142-143, 147, 172). 
General Electric Announces 100-Watt Lamp Giving 

Continuous Flashes (p. 168). 

Bell Laboratories Record 

15 (April, 1937), No. 8 
A New Noise Meter (p. 252). J. M. BARSTOW 


10 (April, 1937), No. 4 

The Acoustical Labyrinth (pp. 24-27, 36). B. J. OLNEY 

Efficiency of Horn Loud Speakers (p. 30). F. MASSA 

10 (May, 1937), No. 5 

Noise in Frequency Modulation (p. 22). H. RODBR 


13 (March 27, 1937), No. 5-6 
A New German Hand Camera "Arriflex" (Neuartige 

Deutsche Handkamera) (p. 49). W. MARTINI 

"Phonorhythm" (Fonorhythmie) (p. 50). P. HATSCHEK 

13 (April 24, 1937), No. 7 

Fragen zur Raumdarstellung (Questions on Stereo- 
scopic Representation) (p. 61). G. TIMMERMANN 
Neuer Richtmikrofone (New Directional Microphone) 

(p. 63) P. HATSCHEK 



Neue Sicherheitsvorschriften fur Lichtspieltheater 
(New Safety Recommendations for Motion Picture 
Theaters) (p. 84). W. GUNTHER 

Kinobild mit Gluhlampenfeldern (Motion Pictures by 

Means of Panels of Incandescent Lamps) (p. 88). P. HATSCHEK 

International Photographer 

9 (May, 1937) No. 4 

New Economical Trick Shot Camera (p. 5). 
Twentieth Century-Fox Silent Camera Proven Success (p. 10). 
New Canady Recording Galvanometer (p. 19). 

9 (June, 1937), No. 5 
Color Make-Up (p. 27). 
"Preview" Moviola Ready for Use (p. 28). 

International Projectionist 

12 (April, 1937), No. 4 

New Amplifier Features Reflect Rapid Progress in 

Design (p. 7). L. CHADBOURNH 

Projection Requisites of the Berthon-Siemens Lenticu- 
lar Color-Film (p. 18). E. GRETENER 

The Push-Pull Sound Recording and Reproducing 

System (p. 19). F. T. JAMEY, JR. 

12 (May, 1937), No. 5 

Film Scratches (p. 7). 

A New Projection Tool: The Cathode-Ray Oscillo- 
scope (p. 12). L. P. WORK 

Effect of New Recordings on Theater Sound Repro- 
duction (p. 16). L. CHADBOURNE 

A New Zero-Current Meter for Projection Room Use 

(p. 22). R. GARWIN 

Kinematograph Weekly 

242 (April 1, 1937), No. 1563 

A New Color Process Employing Quarter-Size Images 
(p. 50). 


19 (April, 1937), No. 4 

Consideration of the Question of Satisfactory Illumi- 
nation in Projection (Betrachtungen zur Frage der 
gunstigsten Projektionsbildbeleuchtung) (p. 67). O. REEB 

The Cameraman's Technical Demands of Raw Film, 
Studio, Printing Establishment, and Theater (Die 
filmtechnischen Anspruche des Kameramanns an 
Rohfilm, Atelier, Kopieranstalt, und Filmtheater) 
(p. 76). A. VON LAGORIO 

Arriflex, A New Professional Hand Camera (Die Arri- 
flex, eine neue Berufshandkamera) (p. 85). 


Outline of Film Standardization (Grundlinien der- Nor- 

mung im Film) (p. 91). W. RAHTS 

19 (May, 1937), No. 6 

Color-Film and Projection (Farbfilm und Projektion) 

(p. 121). W. PAPE 

Ufacolor Process (Das Ufacolor-Verfahren) (p. 125). G. IGNATOW 

Mirror Reflecting Device on Motion Picture Cameras 
(Die Spiegelreflexeinrichtung bei Kinokameras) 
(p. 129). G. SEEBE-R 

Floodlights and Spots with Fresnel Lenses (Schein- 
wefer und Spots mit Stufenlinsen) (p. 130). G. O. STINDT . 

Distortion as Produced by the Variation in Illumina- 
tion along a Scanning Slit (Der optische Klirrfaktor 
von Lichtspaltanordnungen ) (p. 132). A. D. JOTZOFF 

Motion Picture Herald (Better Theaters Section) 

127 (May 1, 1937), No. 5 

How the New Developments in Sound Affect Mainte- 
nance (p. 28). A. NADELL 

127 (May 29, 1937), No 9 
Theater Acoustics Today: Auditorium Form Factors 

(p. 41). C. C. POTWIN 

Photographic Journal 

77 (April, 1937) (new series) 

Photographic Progress During 1936 (p. 193). G. E. MATTHEWS 

Progress in Colour Photography (p. 224). D. A. SPENCER 

The Story of the Cartoon Film (p. 229). E. A. DYER 

Increase in Technical Facilities for British Film Pro- 
duction (p. 233). I. D. WRATTEN 
Developments in Kinematographic Apparatus (p. 238). R. H. CRICKS 
Studio Lighting for Kinematography (p. 245). B. LANGLEY 
Negative-Positive Processing of Dufaycolor Film (p. 

250). G. B. HARRISON 


Photographische Industrie 

35 (March 31, 1937), No. 13 

High-Speed Camera Taking from 16 to 80,000 Pictures 
per Second (Der Zeitdehner der Technik fur 80,000 
bis 16 Aufnahme in der Sekunde) (p. 391). 

35 (April 7, 1937), No. 14 

Stability Testing of Motion Picture Films by Artificial 
.Aging (Haltbarkeitsprufung von Kinofilmes durch 
kunstliche Alterung) (p. 417). 

35 (April 14, 1937), No. 15 
Film Fires (Einiges iiber den Filmbrand) (p. 443). W. NAUCK 

35 (April 21, 1937), No. 16 
Sound Recording by the "Phonorhythm" Method (Die 



[J. S. M. P. E. 

Tonbildaufnahmen nach dem Phonorhythmiever- 
fahren) (p. 467). 

35 (May 19, 1937) No. 35 

Die Bezugsebene fur Distanzeinstellung bei Schmal- 
film-Kinoapparaten (The Relative Plane for Focal 
Setting in Substandard Motion Picture Cameras) 
(p. 581). 

Proceedings of the Institute of Radio Engineers 

25 (April, 1937), No. 4 

Characteristics of American Broadcast Receivers as 
Related to the Power and Frequency of Transmitters 
(p. 387). 

Multiple Amplifier (p. 421). 

Frequency Modulation Noise Characteristics (p. 472). 

Radio Engineering 

17 (April, 1937), No. 4 

Equipment and Methods Used in Routine Measure- 
ments of Loud Speaker Response, II (pp. 16-18, 25). 
The Isochrometer (p. 22). 

17 (May 1937) No. 5 

Equipment and Methods Used in Routine Measure- 
ments of Loud Speaker Response (p. 22). 

La technique cinematographique 

9 (March, 1937), No. 75 

A New Optical Projection Printing Process for Lenticu- 
lated Film in Color Motion Picture Photography 
(Un Nouveau Procede de Copie par Projection Op- 
tique de Films Gauffres pour la Cinematographic en 
Couleurs) (p. 881). 

9 (April, 1937), No. 75 

Qu'est-ce que la Solution Thomson-Houston-DeLassus? 
(What Is the Thomson-Houston-DeLassus Solu- 
tion?) (p. 903). 

L'eclairage du film dans le lecteur de son (Optical 
Systems for Sound-Films) (p. 911). . 

La Cinematographic Francaise 

19 (April 30, 1937), No. 965 

L'Effet Photo- Electrique et Son Application aux 
Cellules (Photoelectric Effect and Its Application to 
Cells) (p. 1). 


10 (April, 1937), No. 110 
We See Scophony's Latest System (p. 196). 













July, 1937] 



Scanning Faults and How to Remedy Them (p. 200). G. PARR 
Transformers for Television Scanning (p. 209). G. A. V. SOWTER 

The Design of Vision- Frequency Amplifiers, II (p. 220). P. NAGY 

10 (May, 1937), No. Ill 

Magnetic Scanning Defects and Their Causes (p. 268). I. G. MALOFF 
The First Acorn Valve Receiver for Vision Signals 

(p. 273). 
The Design of Vision-Frequency Amplifiers, III 

(p. 279). P. NAGY 


Harry Pfannenstiehl, a member of the Technical Staff of Bell Tele- 
phone Laboratories, and of the Society of Motion Picture Engineers, 
died suddenly on May 29, 1937, of heart trouble, from which he had 
suffered for several years. He was born in New York City on April 
24, 1887. His father was Adolph L. and his mother, Anna N. (Dossen- 


bach) Pfannenstiehl, both of whom were born in Germany, but who 
had moved to the United States during their youth. 

In March, 1911, he joined the Engineering Department of the 
Western Electric Company with whom he continued until 1925, when 
the Bell Telephone Laboratories was formed. He had been with the 
Laboratories continuously until his death, thus completing over 
twenty-six years with the Bell System. 

In April, 1913, he was transferred by the Western Electric Com- 
pany to their branch in Antwerp, Belgium,- where he was employed 
for about a year and a half. 


Since the World War, Mr. Pfannenstiehl- had been engaged in a 
considerable number of special developments for the Western Elec- 
tric Company and Bell Telephone Laboratories where the design of 
equipment has involved unusual problems with respect to ingenuity 
of operating mechanisms, choice of materials for dynamic properties, 
or extreme precision requirements. In the early developments of 
the printing telegraph, he played a very substantial part. He was 
principally responsible for the mechanics not only of telephoto trans- 
mitting and receiving machines of 1925, but also of the recent tele- 
photo equipment used by the Associated Press. 

To the commercializing of sound picture apparatus, he contributed 
by responsibility for much of the design of studio sound recording 
machines and of theater sound-projecting equipment. In this work 
he made a specialty of devices for driving the film uniformly; and 
many of the improvements in sound quality that have resulted from 
the recent perfection of these machines are attributable to his skill. 

Mr. Pfannenstiehl contributed many papers to the scientific litera- 
ture, several of which have been published in the JOURNAL of the 




MAY 24-28, 1937 

As Conventions come and go it would seem that each is more successful than 
the preceding. However, it can be safely stated that the recent Convention in 
Hollywood was by far the most successful of all that have been held by the Society 
on the western coast, and it is doubtful whether any other Convention has ever 
exceeded this one in point of interest, attendance, and participation. The number 
of paid registrations was greater than at all previous conventions, and the at- 
tendance at the technical sessions, from the first session on Monday morning to 
the last session on Friday evening, was indicative of the increasing interest of 
the Hollywood engineers and technicians in the activities of the Society. 

The evening sessions were especially interesting and capacity audiences were 
attracted to each one. The gratitude and appreciation of the Society and the 
Board of Governors was expressed by President Wolf in his closing remarks on 
Friday evening to the Society officers on the West Coast, to the Board of Managers 
of the Pacific Coast Section, and to the officers of the Research Council of the 
Academy of Motion Picture Arts & Sciences. One of the highlights of the week 
was the special Thursday evening session of the Academy Research Council, ar- 
ranged through the courtesy of William Koenig, Chairman, and Nathan Levinson, 
Vice- Chairman of the Council. The Society is also greatly indebted to Gordon 
S. Mitchell, Manager of the Research Council, and the members of his staff for 
their excellent cooperation and generous assistance. 


The Convention opened at 10 A.M. on Monday (May 24th) with a brief presi- 
dential address by Mr. S. K. Wolf; several Committee reports, including the 
comprehensive Progress Committee's Annual Report; and two papers on applica- 
tions of motion pictures. 

The customary Informal Luncheon was held at noon in the Florentine Room of 
the Hotel, during which the members of the Society were addressed briefly by 
President Wolf and Major Nathan Levinson, of Warner Bros. Studios, Raymond 
Hatton, well known comedian, and various members of the Board of Managers 
of the Pacific Coast Section. An official photograph of the delegates was made on 
the Patio immediately following the luncheon. 

The highlight of the Monday afternoon session, which dealt with studio mat- 
ters, was probably the paper describing "A New Viewpoint on the Lighting of 
Motion Pictures," by G. Gaudio, well known cinematographer of Hollywood. In 
arriving at his new view-point in lighting technic, Mr. Gaudio first traced the de- 
velopment of the studio lighting art to show the gradual evolution of the technic 
into its present-day form. Other papers, as listed in the program printed on the 
following pages, completed a well-rounded session on the engineering problems 


and developments in modern motion picture studios. - The paper by L. Fermaud, 
describing "The London Film Studios at Denham, England" was particularly in- 
teresting in this respect. 

The evening of Monday, May 24th, was devoted to an all-Technicolor program 
of recent feature and short subjects, including the new release A Star Is Born. 
This entire session was arranged through the courtesy of Mr. G. F. Rackett, 
Vice-President of Technicolor Motion Picture Corporation. 

The morning of Tuesday, May 25th, was devoted to the problems of color motion 
pictures. Considerable interest was shown in the papers dealing with the new 
Agfacolor process and color-print processes. In connection with the latter presen- 
tation, by O. O. Ceccarini,' a comprehensive exhibit of color-stills by various 
studios and leading color photographers throughout the country was on display 
in one of the parlors of the Hotel during the entire Convention. 

The afternoon session was marked by a particularly interesting paper by H. E. 
A. Joachim, of Dresden, Germany, describing "Twenty Years of Development 
of High-Frequency Cameras." The latter part of the afternoon was devoted to 
a symposium on transmission meters, and provided considerable technical ma- 
terial on up-to-date methods of recording and measuring sound transmission 

One of the most outstanding some would perhaps say the most outstanding 
sessions of the Convention was the one held at the Universal Studios on the 
evening of Tuesday, May 25th, at which a complete demonstration was given of 
"How Motion Pictures Are Made." A complete description of the proceedings 
of the evening will be published in a forthcoming issue of the JOURNAL, but it is 
well at this point to register the thanks of the Society to those who worked so hard 
to make the evening an outstanding success. Thanks are due particularly to Mr. 
Charles R. Rogers, Vice-President in Charge of Production, and to Mr. Homer 
G. Tasker, Sound Supervisor of the Universal Studios. 

About 450 or 500 delegates and their friends assembled at 8 P.M. on one of the 
sound stages, where they were welcomed to Universal by Mr. Val Paul, Studio 
Manager. Then followed a paper by Mr. Robert Presnell, Associate Producer, 
in which were described the methods and problems involved in preparing stories 
for production. With particular reference to a scene in the forthcoming picture, 
One Hundred Men and a Girl, starring Deanna Durbin, a paper by John Harkrider, 
Supervising Art Director (presented by Michael Fitzmaurice), discussed the 
problem of "Set Design from Script to Stage." An artist and an architectural 
member of the studio demonstrated with crayon and pencil how the preliminary 
sketches are made in planning the sets to conform to the ideas of the authors of 
the stories. Then followed a paper by Bernard Brown, Chief Music and Dubbing 
Mixer, on "Prescoring for Song Sequences." The procedure as described in the 
paper was demonstrated by an actual recording of the voice of Miss Deanna 
Durbin singing a song to a playback orchestral accompaniment which was later 
to be dubbed into the picture shot on the stage designed by the artists as described 

Adjourning now to the projection stage, the members were treated to a complete 
demonstration of how motion pictures are photographed. A complete crew of 
cinematographers, lighting men, director, and actors (Mischa Auer and Deanna 
Durbin) all participated in demonstrating the procedure, to the accompaniment 

108 FALL CONVENTION [J. s. M. P. E. 

of an informal description of the procedure by Mr. Tasker. When the shot was 
completed, the group again convened on the sound stage and saw the projection of 
the completed picture which had been photographed and recorded as here de- 
scribed. (It is hardly necessary to state, of course, that the finished scene, as 
projected, was not the actual one shot during this evening's session; such would 
have been impossible in view of the time required for processing, etc.) 

Concluding the evening, various shots were projected to show the effects upon 
the "mood" of the picture of various kinds of background music, as discussed by 
Charles Previn, Musical Director, and to demonstrate also the manner of rough 
cutting and editing pictures, as described by Maurice Pivar, Supervising Editor. 
A particularly interesting demonstration was given 'by Edwin Wetzel, Dubbing 
Mixer, during which he went through the actual procedure of mixing a number 
of sound effects into a picture that was projected first with dialog only and later 
with the sound effects added. 

The morning of Wednesday, May 26th, was devoted principally to acoustic < 
and sound, one of the outstanding papers of the session being the one on "Recent 
Progress in Acoustics," by V. O. Knudsen. The papers on an "Improved Noise- 
Reduction System," by Hasbrouck, Baker, and Batsel, and on "A Device for 
Direct Reproduction from Variable- Density Sound Negatives," by M. J. Alber- 
sheim, aroused considerable interest among those attending the meeting. 

The afternoon of Wednesday was devoted to a visit to the Studios of the 
Twentieth Century-Fox Film Corporation at Beverley Hills, during which the 
members were escorted throughout the lot and the various stages. 

The Semi-Annual Banquet was held in the Blossom Room of the Hotel on the 
evening of the same day. The evening was devoted in its entirety to dining and 
entertainment, as it was felt that the rigors of the long technical sessions war- 
ranted dispensing with formalities on that evening. 

Thursday afternoon (May 27th) was devoted to papers and presentations deal- 
ing with laboratory and projection problems. A paper by Captain J. G. Bradley, 
dealing with the "Changing Aspects of the Film Storage Problem," contained in- 
teresting information on experiments recently conducted with regard to the in- 
flammability of film in storage cabinets. A paper by J. M. Nickolaus on "Toning 
Positive Film by Machine Methods" described the procedure followed in toning 
the recent feature The Good Earth at the Metro-Goldwyn-Mayer Studios. The 
session included also papers on the design of a densitometer and the measurement 
of density and graininess, which aroused considerable discussion, and on the ap- 
plication of pH. control to photographic fixing baths and other solutions. 

Another outstanding session of the Convention was held on the evening of 
Thursday at the M-G-M Studios at Culver City; namely, a meeting of the Re- 
search Council and the Technicians Branch of the Academy of Motion Picture 
Arts & Sciences, to which the members and guests of the SMPE were invited. 
An outstanding presentation of the evening was the paper on "The Work of the 
Committee on Standardization of Theater Sound Projection Equipment Char- 
acteristics," by J. K. Hilliard, Chairman of the Academy Committee. This 
paper described the work of the Committee in connection with the establishment 
of theater equipment characteristics. The evening concluded with the projection 
of a number of scenes from outstanding films, illustrating sound quality, special 
effects, and unusual photography. 

July, 1937] FALL CONVENTION 109 

The morning session of Friday, May 28th, was devoted to an apparatus sym- 
posium and miscellaneous papers on magnetic recording, the use of infrared nega- 
tive, laboratory equipment, etc. The afternoon of Friday was devoted to a group 
of papers on 16-mm. and 35-mm. sound recording and reproduction, including the 
report of the Standards Committee, and a description of the new SMPE 16-mm. 
Sound Test-Film, by M. C. Batsel. A new 16-mm. sound projector was described 
and demonstrated effectively by E. C. Fritts and O. Sandvik and examples of 
very fine class A push-pull recordings were demonstrated by G. L. Dinunick. 

The closing session of the Convention on Friday evening, at which Mr. Ralph 
R. Beal, Research Supervisor of the Radio Corporation of America, presented a 
description of the RCA system of television, was attended by perhaps 450 or 500 
members and guests of the Society. 


As pointed out previously, the success of the Convention was due to the efforts 
of a large number of officers, members, and friends of the Society. Credit is due 
particularly to the efforts of Mr. W. C. Kunzman, Convention Vice-President; 
Mr. H. G. Tasker, Past-President; Mr. J.I. Crabtree, Editorial Vice-President; 
Mr. G. E. Matthews, Chairman, Papers Committee; Messrs. H. Griffin and J. 
Frank, Jr., in charge of projection facilities; Mr. W. A. Mueller, Chairman; and 
Mr. L. A. Aicholtz, Secretary, West Coast Local Papers Committee; to the Board 
of Managers of the Pacific Coast Section; Mr. K. F. Morgan, Chairman; Mr. G. F. 
Rackett, Past Chairman of the Section, and Executive Vice-President of the Society; 
Mr. G. A Chambers, Secretary-Treasurer; and Messrs. J. O. Aalberg and H. W. 
Moyse, Managers. The officers and members of Los Angeles Local No. 150 
I.A.T.S.E. are particularly to be thanked for their generous assistance in con- 
nection with the projection of all the motion pictures throughout the entire Con- 
vention session. Appreciation is also expressed to the American Society of Cine- 
matographers for supplying a number of papers by members of their Society. 

Acknowledgement for their generous assistance is also due to P. Mole, Chairman, 
Local Arrangements Committee; Mrs. K. F. Morgan and Mrs. P. Mole, hostesses; 
and Messrs. C. W. Handley, E. Huse, and G. F. Rackett, for their assistance in 
connection with transportation, hotel accommodations, banquet, etc. 

Among the companies and studios that should be thanked for their coopera- 
tion in providing various facilities of the Convention, and for their great cordiality 
in receiving the members at the studios, are the following: National Carbon 
Company; International Projector Corporation; National Theater Supply Cor- 
poration; Raven Screen Company; Electrical Research Products, Inc.; Bausch 
& Lomb Optical Company; General Electric Company ; Mole Richardson, Inc.; 
Enterprise Optical Company; General Electric Supply Company; and Dicta- 
phone Products Corporation, all of which collaborated in making available the 
equipment used during the technical sessions. Universal Studios, M-G-M 
Studios, and Twentieth Century-Fox Film Studios are to be thanked for enter- 
taining the delegates and making available the facilities of their plants. Thanks 
are due also to the Fox West Coast Theaters, Warner Bros. Hollywood Theater, 
and Pantages Theater for supplying passes to members and guests during the 
week of the Convention, and to Warner Bros. Studios for supplying the enter- 
tainment features for the banquet 




9:00 a. m. Business and General Session. G. F. Rackett, Chairman. 

10:00 a. m. Opening Remarks by President S. K. Wolf. 

Report of the Convention Committee; W. C. Kunzmann, Conven- 
tion Vice- President. 

Report of the Membership Committee; E. R. Geib, Chairman. 

Report of the Papers Committee; G. E. Matthews, Chairman. 

"Progress in the Motion Picture Industry:" Report of the Progress 
Committee; J. G. Frayne, Chairman. 

Report of the Historical Committee; E. Theisen, Chairman. 

"Soft X-Ray Motion Pictures of Small Biological Specimens;" 
H. F. Sherwood, Kodak Research Laboratories, Rochester, N. Y. 

"Educational Film Progress and Problems;" S. K. Wolf, Erpi 
Picture Consultants, Inc., New York, N. Y. (Demonstration.) 

12:30 p. m. Informal Luncheon. 

Studio Session. K. F. Morgan, Chairman. 
2:00 p. m. "The London Film Studios at Denham, England;" L. C. Fermaud- 

London Film Productions, Ltd., Denham, Middlesex, England. 
"The Evolution of Special- Effects Photography from an Engineering 

Viewpoint;" F. W. Jackman, Hollywood, Calif. (Demonstration.) 
"Special Engineering Problems in a Motion Picture Studio;" 

W. Strohm, Twentieth Century-Fox Film Corp., Hollywood, 

"A New Viewpoint on the Lighting of Motion Pictures ;" G. Gaudio, 

A. S. C., Hollywood, Calif. (Demonstration.) 
"Recent Developments in Motion Picture Set Lighting Equipment ;" 

E. C. Richardson, Mole-Richardson, Inc., Hollywood, Calif. 
"Light-Weight Stage Pick-Up Equipment;" L. D. Grignon, Para- 
mount Productions, Inc., Hollywood, Calif. 

8:30 p. m. An all-Technicolor program of recent feature and short subjects. 

Color Session. J. A. Ball, Chairman. 

10:00 a. m. "Color Print Processes;" O. O. Ceccarini, Metro-Goldwyn-Mayer 
Studios, Culver City, Calif. A comprehensive exhibit of color 

* As actually followed at the meetings. 


stills by various studios and leading color photographers through- 
out the country was on display during the Convention by the 
following contributors: 


New York New York 


M-G-M Studios, Hollywood New York 


Rochester South Orange, N. J. 


Los Angeles Chicago 


Rochester New York 


Photographic Div., Detroit New York 

New York 

"The New Agfacolor Process;" J. L. Forrest and F. M. Wing, 

Agfa Ansco Corporation, Binghamton, N. Y. 
Report of the Color Committee; J. A. Ball, Chairman. 
"Advanced Technic of Technicolor Lighting;" C. W. Handley, 

National Carbon Co., Cleveland, Ohio. 
"Some Lighting Problems in Color Cinematography;" T. T. Baker, 

Dufaycolor, Inc., New York, N. Y. (Demonstration.) 

Instruments Session. Douglas Shearer, Chairman. 

2:00 p.m. "Twenty Years of Development in High-Frequency Cameras;" 
H. E. A. Joachim, Zeiss-Ikon Aktiengesellschaft, Dresden, 

"A High-Precision Sound-Film Recording Machine;" H. Pfannen- 
stiehl, Bell Telephone Laboratories, Inc., New York, N. Y. 

"A Dynamic Light-Valve;" E. Gerlach, Klangfilm G. m. b. H., 
Berlin, Germany. 

"A Laboratory Flutter-Measuring Instrument;" R. R. Scoville, 
Electrical Research Products, Inc., Hollywood, Calif. 

"Power Level Indicator for Sound Recording;" F. L. Hopper, Elec- 
trical Research Products, Inc., Hollywood, Calif. 

Symposium on Transmission Meters. 

4:00 p. m. "A Transmission-Measuring System Utilizing a Graphic Recording 
Meter;" W. W. Lindsay, Jr., General Service Studios, Holly- 
wood, Calif. 

"A New Instrument for Producing Automatically a Graphic Record 
of Audio-Frequency Characteristics;" A. D. MacLeod, Tobe 
Deutschmann Corporation, Canton, Mass. (Demonstration.) 

"A Continuous Level Recorder for Routine Studio and Theater 



[J. S. M. P. E. 

Measurements;" G. M. Sprague and J. K. Milliard, Metro- 
Goldwyn-Mayer Studios, Culver City, Calif. 

"A Curve-Plotting Transmission Meter;" L. A. Aicholtz, Universal 
Pictures Corporation, Universal City, Calif. 

"A Curve-Plotting Transmission Meter;" L. D. Grignon, Para- 
mount Productions, Inc., Hollywood, Calif. 

8:00 p. m. Studios of Universal Pictures Corporation, Universal City, Calif. ; 

Special Evening Demonstration: "How Motion Pictures 

Made." Homer G. Tasker, Chairman. 
Assemble on Stage 10. 
Motion Picture Cartoon. 

Welcome to Universal Val Paul, Studio Manager. 
"Preparing a Story for Production;" Robert Presnell, Associate 

Producer. (Story conference, shooting scripts, scheduling players, 

and equipment.) 
"Prescoring for Song Sequences;" Bernard Brown, Chief Music 

and Dubbing Mixer. (Demonstration.) 
"Set Design from Script to Stage," illustrated by the set used for 

remainder of this program; John Harkrider, Supervising Art 

Director. Presented by Michael Fitzmaurice. (Demonstration) 
Adjourn to production stage. 
"Production Handling of Lighting Equipment;" Frank Graves, 

Superintendent Electrical Department. (Demonstration.) 
"Lighting a Long Shot and Close-Up;" Joe Valentine, Director of 

Photography. (Demonstration.) 

"Sound Pick-Up on a Long Shot and Close-Up;" Joe Lapis, Pro- 
duction Mixer. (Demonstration.) 
"The Director's Problem;" Joseph Pasternak, Associate Producer. 

( Demonstration . ) 
Return to Stage 10. 

Projection of "dailies" made in the demonstration above. 
"Editing Motion Pictures;" Maurice Pivar, Supervising Editor. 

"Setting Music to Motion Pictures;" Charles Previn, Musical 

Director. (Demonstration.) 
"Assembling a Final Sound-Track;" Edwin Wetzel, Dubbing 

Mixer. (Demonstration.) 


Acoustics and Sound Session. William Mueller, Chairman. 
10:00 a. m. "Recent Progress in Acoustics;" V. O. Knudsen, Professor of 

Physics and Dean of Graduate Study, University of California, 

Los Angeles, Calif. 
"Mathematical Relations between Grain, Background Noise, and 

Characteristic Curve of Sound-Film Emulsions;" W. J. Albers- 

heim, Electrical Research Products, Inc., New York, N. Y. 

July, 1.937] FALL CONVENTION 113 

"Improved Noise-Reduction System for High-Fidelity Recording;" 
H. J. Hasbrouck, J. O. Baker* and C. N. Batsel, RCA Manu- 
facturing Co., Inc., Camden, N. J., and Hollywood, Calif. 

"A Device for Direct Reproduction from Variable-Density Sound 
Negatives;" W. J. Albersheim, Electrical Research Products, 
Inc., New York, N. Y. 

"Sound Pick-Up Methods for Motion Pictures;" J. P. Maxfield, 
A. W. Colledge, and R. T. Friebus, Electrical Research Products, 
Inc., New York, N. Y. 

"A Dubbing Rehearsal Channel;" H. G. Tasker, Universal Pictures 
Corp., Universal City, Calif. 

"An Automatic Sound-Track Editing Machine;" G. M. Best, 
Warner Brothers Pictures, Inc., Burbank, Calif. 

2:30 p. m. Visit to Twentieth Century-Fox Film Corporation, Beverly Hills, 

7:30 p. m. Blossom Room; Semi- Annual Banquet. 

10:00 a. m. Open Morning. 

Laboratory and Projection Session. Harry Ensign, Chairman. 
1:10 p. m. "Changing Aspects of the Film Storage Problem;" Capt. J. G 
Bradley, National Archives, Washington, D. C. (Demonstration.) 

Report of the Projection Practice Committee; H. Rubin, Chairman. 

Report of the Exchange Practice Committee; A. W. Schwalberg, 

"A Wide-Range Linear-Scale Photoelectric Cell Densitometer ;" 
W. W. Lindsay, Jr., General Service Studios, Inc., Hollywood, 
Calif., and W. V. Wolfe, RCA Manufacturing Co., Inc., Holly- 
wood, Calif. 

"Standardization of Photographic Density;" C. M. Tuttle and 
A. M. Koerner, Kodak Research Laboratories, Rochester, N. Y. 

"Objective Quantitative Determination of Graininess in Photo- 
graphic Emulsions;" A. Goetz, Associate Professor of Physics, 
and W. O Gould, California Institute of Technology, Pasadena, 

"Sound-Track Blooping;" F. D. Williams, Williams Laboratory, 
Hollywood, Calif. (Demonstration.) 

"Toning Positive Film by Machine Methods;" J. M. Nickolaus, 
Metro-Goldwyn-Mayer Corporation, Culver City, Calif. (Dem- 

"Fixing Baths and Their Properties;" J. I. Crabtree, H. Parker, Jr., 
and H. D. Russell, Kodak Research Laboratories, Rochester, 
N. Y. 

"Practical Applications of pH Control in Motion Picture Process- 
ing;" D. K. Allison, Chemical and Research Corporation, Holly- 
wood, Calif. 


8:00 p. m. Metro-Goldwyn-Mayer Studios, Culver City, Calif. 

Meeting of the Research Council and the Technicians' Branch 

the Academy of Motion Picture Arts and Sciences; William Kc 
Chairman, Research Council; Major N. Levinson, Vice- Chair 
man, Research Council, and Chairman, Technicians' Branch. 

"Observations on Hollywood Production in Relation to the 
duction of Army Training Films;" Capt. R. T. Schlosberg, U. 
Army Signal Corps ; now on duty as a student with the Academj 
of Motion Picture Arts and Sciences. 

"Cooperative Technical Program of the Research Council of tl 
Academy of Motion Picture Arts and Sciences;" W. Koenig, 
Chairman, Research Council. 

"The Work of the Committee on Standardization of Theater Sound 
Projection Equipment Characteristics;" J. K. Milliard, Chairman. 

Projection and Discussion of Outstanding Films Illustrating 
Sound Quality, Special Effects, Unusual Photography. Ar- 
ranged by the technicians of the Hollywood studios. 


Apparatus Symposium, Peter Mole, Chairman. 

10:00 a. m. "The Super Simplex Pedestal;" J. Frank, Jr., International Pro- 
jector Corporation, New York, N. Y. 

"Complete Cue-Mark Elimination Plus an Automatic Change- 
Over;" J. P. Pollanz and S. A. MacLeod, Los Angeles, Calif. 

"Magnetic Recording-Reproducing Machine for Objective Speech 
Study;" S. J. Begun. New York, N. Y. (Demonstration.) 

"Infrared Negative as Applied to Special-Effects Photography;" 
G. W. Hough and W. Leahy, Agfa Ansco Corporation, Holly- 
wood, Calif. (Demonstration.) 

"Laboratory Equipment for the Smaller Laboratory;" Arthur 
Reeves, Hollywood, Calif. 

"Two New Films for Duplicating Work;" Eastman Kodak Com- 
pany, Hollywood, Calif. (Demonstration.) 

"A New Type Double-Film Attachment;" E. C. Manderfeld, 
Electrical Research Products, Inc., Hollywood, Calif. 

"A Combined Viewing and Projection Machine with or without 
Sound;" I. Serrurier, Moviola Co., Hollywood, Calif. (Demon- 

Sound Equipment Symposium. . H. Hanson, Chairman. 
2:00 p. m. "Present Aspects in the Development of 16-Mm. Sound;" A. 
Shapiro, The Ampro Corporation, Chicago, 111. (Demonstration.) 

Report of the Non-Theatrical Equipment Committee; R. F. 
Mitchell, Chairman. 

"The SMPE 16-Mm. Sound Test-Film;" M. C. Batsel. (Demon- 

July, 1937] FALL CONVENTION 115 

"A Sound Kodascope;" E. C. Fritts and O. Sandvik, Eastman 

Kodak Company, Rochester, N. Y. (Demonstration.) 
Report of the Standards Committee; E. K. Carver, Chairman. 
Report of the Sub-Committee on Film Perforation; J. A. Dubray, 

"A Combination Picture and Non-Slip Ultraviolet Automatic 

Printer;" O. B. Depue, Chicago, 111. (Demonstration.) 
"The RCA Recording System and Its Adaptation to Various Types 

of Sound-Track, with Demonstration of Recent Recordings of the 

Class A Push-Pull Type;" G. L. Dimmick, RCA Manufacturing 

Co., Inc., Camden, N. J. 
"A Linear Decibel Scale Volume Indicator;" F. G. Albin, United 

Artists Studio Corporation, Hollywood, Calif. 

8:00 p. m. Television Session. S. K. Wolf, Chairman. 

"RCA Developments in Television;" Ralph R. Bcal, Research 
Supervisor, Radio Corporation of America, New York, N. Y. 

(Illustrated with slides and motion pictures.) 



The next Convention of the Society will be held at New York, N. Y., at the 
Hotel Pennsylvania, October llth to 14th, inclusive. Work has already been 
begun by the Papers Committee under the Chairmanship of G. E. Matthews, 
and members are urged to take advantage of this early announcement of the 
dates of the Convention by giving some thought to the presentations and demon- 
strations they may wish to make. All those having such plans in mind should 
communicate as early as possible with the Chairman of the Papers Committee. 

Special hotel rates, guaranteed to SMPE delegates, European plan, will be as 

One person, room and bath $ 3.50 

Two persons, double bed and bath 5.00 

Two persons, twin beds and bath 6.00 

Parlor suites 1 1 .00 up 

Room reservation cards will be mailed to the membership of the Society in the 
near future, and everyone who plans to attend the Convention should return his 
card to the Hotel promptly in order to be assured of satisfactory accommodations. 
Special garage rates will be provided for SMPE delegates who motor to the 


Ballots for nomination of Officers of the Society for 1938 have already been 
mailed to the voting membership of the Society, and final nominations will be 
made by the Board of Governors at the next meeting, to be held on July 9th at 
New York. 

Officers and Governors whose terms expire December 31, 1937, are as follows: 

G. F. RACKETT, Executive Vice-President 
L. A. JONES, Engineering Vice-P resident 
O. M. GLUNT, Financial Vice-President 
J. FRANK, JR., Secretary 
L. W. DAVEE, Treasurer 
A. S. DICKINSON, Governor 
A. C. HARDY, Governor 
H. GRIFFIN, Governor 

The Executive Vice-President, Secretary, and Treasurer are to be elected for 
one-year terms; the remaining officers for two-year terms. 




As announced in the previous issue of the JOURNAL, the next meeting of the 
Progress Award Committee will be held on July 6th, at which time all nominations 
for the Progress Medal received by the Committee will be considered, and the 
Committee's report to the Board of Governors drafted. 

The regulations pertaining to the Progress Award were given in detail in the 
June issue of the JOURNAL. 


At a recent meeting of the Admissions Committee, at the General Office of the 
Society, the following applicants for membership were admitted to the Associate 
grade : 


1116 N. New Hampshire St., 

Los Angeles, Calif. 

Kiev Ulitza Korolenko, 
dom 34, kv. 2, 
U. S. S. R. 
BELL, D. G. 
6910 San Mateo Blvd., 

Dallas, Texas. 
605 N. Ervay St., 

Dallas, Texas. 

166 Washington St., 

Binghamton, N. Y. 
.5312 244th St., 

Douglas ton, N. Y. 

117 N. San Pedro St., 

Los Angeles, Calif. 
4109 Northcliffe Ave., 

Montreal, Canada. 
45 E. 49th St., 

New York, N. Y. 
Lix, E. C. 

1369 N. Wilton Place, 
Hollywood, Calif. 


Don Lee Broadcasting System, 
Seventh & Bixel Sts., 
Los Angeles, Calif. 
"The Moorings," 
Osborne Road, 
Potters Bar, 
Hertfordshire, England. 

Dominion Sound Equipments, Ltd. 
820 Cambie St., 
Vancouver, B. C. 
5436 School St., 
Chicago, III. 


Monastyrskaja 11, Kiev, 

U. S. S. R. 
22 The Green, 
Dover, Del. 


232 Beach 141st St., 
Bell Harbor, N. Y. 

581 Monterey Road, 

Glendale, Calif. 
506 W. 61st Place, 
Chicago, 111. 



In addition, the following applicants have been admitted by vote of the Board 
of Governors to the Active grade: 


Electrical Research Products, Inc., 
250 W. 57th St., 
New York, N. Y. 


2 E. 86th St., 

New York, N. Y. 
1217 Taft Bldg., 

Hollywood, Calif. 

The Museum of Modern 
Art Film Library, 
485 Madison Ave., 
New York, N. Y. 

47 W. 68th St., 

New York, N. Y. 

Film Automatic Machine Corp. 
17 Nelson St., 
Bloomfield, N. J. 


Defender Photo Supply Co. 
Driving Park, 
Rochester, N. Y. 

Du Pont Club, 
Parlin, N. J. 


RCA Manufacturing Co., Inc., 
Camden, N. J. 




Volume XXIX AUGUST, 1937 Number 2 



RCA Developments in Television R. R. BEAL 121 

Television from the Standpoint of the Motion Picture Produc- 
ing Industry Report of the Scientific Committee of the 
Research Council of the Academy of Motion Picture Arts 

& Sciences 144 

Report of the Standards Committee 149 

Report of the Western Museum Committee 151 

Report of the Papers Committee 154 

A New Viewpoint on the Lighting of Motion Pictures 

G. GAUDIO 157 

The Advanced Technic of Technicolor Lighting 

C. W. HANDLEY 169 

Recent Developments in Motion Picture Set Lighting 

Power-Level Indicators for Sound Recording. . . .F. L. HOPPER 184 

Light- Weight Stage Pick-up Equipment L. D. GRIGNON 191 

Special Engineering Problems in a Motion Picture Studio 

W. T. STROHM 197 
New Motion Picture Apparatus 

A High-Precision Sound-Film Recording Machine 


A Laboratory Flutter-Measuring Instrument R. R. SCOVILLE 209 
Magnetic Recording-Reproducing Machine for Objective 

Speech Study S. J. BEGUN 216 

Frederick Eugene I ves 1856-1937 219 

Current Literature 222 

Fall Convention New York, N. Y., October 11-14, 1937 224 

Society Announcements 227 





Board of Editors 

J. I. CRABTRBE, Chairman 



Subscription to non-members, $8.00 per annum; to members, $5.00 per annum, 
included in their annual membership dues; single copies, $1.00. A discount 
on subscriptions or single copies of 15 per cent is allowed to accredited agencies. 
Order from the Society of Motion Picture Engineers, Inc., 20th and Northampton 
Sts., Easton, Pa., or Hotel Pennsylvania, New York, N. Y. 
Published monthly at Easton, Pa., by the Society of Motion Picture Engineers. 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General and Editorial Office, Hotel Pennsylvania, New York, N. Y. 

West-Coast Office, Suite 226, Equitable Bldg., Hollywood, Calif. 
Entered as second class matter January 15, 1930, at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. Copyrighted, 1937, by the Society of 
Motion Picture Engineers, Inc. 

Papers appearing in this Journal may be reprinted, abstracted, or abridged 
provided credit is given to the Journal of the Society of Motion Picture Engineers 
and to the author, or authors, of the papers hi question. Exact reference as to 
the volume, number, and page of the Journal must be given. The Society is 
not responsible for statements made by authors. 


President: S. K. WOLF, 100 E.42nd St., New York, N. Y. 
Past-President: H. G. TASKER, Universal City, Calif. 

Executive Vice-President, G. F. RACKETT, 823 N. Seward St., Hollywood, Calif. 
Engineering Vice-President: L. A. JONES, Kodak Park, Rochester, N. Y. 
Editorial Vice-President: J. I. CRABTREE, Kodak Park, Rochester, N. Y. 
Financial Vice-President: O. M. GLUNT, 463 West St., New York, N. Y. 
Convention Vice-President: W. C. KUNZMANN, Box 6087, Cleveland, Ohio. 
Secretary: J. FRANK, JR., 90 Gold St., New York, N. Y. 
Treasurer: L. W. DAVEE, 250 W. 57th St., New York, N. Y. 


M. C. BATSEL, Front and Market Sts., Camden, N. J. 

A. S. DICKINSON, 28 W. 44th St., New York, N. Y. 

G. FRIEDL, JR., 250 W. 57th St., New York, N. Y. 

A. N. GOLDSMITH, 444 Madison Ave., New York, N. Y. 

H. GRIFFIN, 90 Gold St., New York, N. Y. 

A. C. HARDY, Massachusetts Institute of Technology, Cambridge, Mass. 

K. F. MORGAN, 7046 Hollywood Blvd., Los Angeles, Calif. 

C. H. STONE, 205 W. Wacker Drive, Chicago, 111. 

R. R. BEAL** 

Summary. A brief review is given of the studies made of the several characteristics 
of television images and other factors that have been effective in establishing standards, 
in determining satisfactory performance, and in guiding the step-by-step develop- 
ment of the RCA electronic system of high-definition television. 

The system employs the "Iconoscope," a cathode-ray tube for translating the visual 
image into electrical impulses, and the "Kinescope" for transforming the electrical 
impulses back into the variations of light-intensity to reproduce the image. The 
sensitivity and characteristics of the "Iconoscope" as a pick-up device are discussed. 

The fundamentals of the RCA high-definition television system now under ex- 
perimental field test in the New York area and the standards presently employed are 
reviewed. Photographs of the studios and other parts of the field-test facilities are 
included. A brief review is given to indicate the progress made and the results at- 
tained up to the present time in these field tests. 

The technic of formulating and presenting television programs is peculiar to the 
requirements of television. The development of the technic is presently related to 
programs employing artists in studios, outside pick-ups, and motion picture film. 
The requirements of program technic are discussed. 

Television and motion pictures have in common the objective of 
reproducing on a viewing screen images that appear to the eye to 
have uninterrupted motion. While some of the fundamentals through 
which this objective is attained in the two arts may be closely re- 
lated, others are widely different. Objectively and to some extent 
technically, the problems parallel in the illumination of the subject, 
in creating the illusion of motion, in realizing an acceptable standard 
of definition, and in obtaining appropriate brightness and size of re- 
produced image on the viewing screen. An outstanding difference 
appears in the system by which the reflected light from the subject 
is transmitted to the viewing screen. 

In motion pictures, the reflected light from the subject is converted 
into a film record, and transmission from the film record to the view- 
ing screen is effected through the agency of light. In television, 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received May 
19, 1937. 

** Supervisor of Research, Radio Corporation of America, New York, N. Y. 




[J. S. M. P. E. 

transmission is effected through the agency of electricity. Reflected 
light from the subject is converted into electrical impulses. These 
may be transmitted by radio or by special cables from the point at 
which the subject is located to a point far removed from that locality, 
and then reconverted into light-images upon the viewing screen. 
The reproduced image may originate from a subject or from a film 
record of a subject. 

The development of a television system by which images of high 
definition may be transmitted electrically and reproduced on a view- 
ing screen has required intensive research by RCA for a period of 
more than ten years. This research has passed through many stages, 
beginning with early mechanical arrangements and advancing to the 





FIG. 1. Elements of the Carey system. 

present all-electronic system now under field test in the New York 
City area. 

Some of the requirements of a high-definition system may be indi- 
cated by a brief description of a system patterned after a suggestion 
made by Carey about 1875. The elements of this system are illus- 
trated in Fig. 1. A pick-up area is constructed of a bank of photoelec- 
tric cells and a viewing screen of a like number of incandescent lamps. 
Each photocell in the bank is connected by an electrical circuit 
through an amplifier to the correspondingly positioned lamp in the 
viewing screen. When the light-image to be transmitted is focused 
upon the bank of photocells, electric current then will flow through 
the circuits connecting those of the photocells that receive light to 
the corresponding lamps in the viewing screen, and a reproduction 
of the subject will appear as an illuminated picture. 

In this system, the amount of detail that can be transmitted is 
limited by the physical dimensions of the individual photocells in the 
pick-up area. Each photocell represents an element of picture area, 

Aug., 1937] 



and the detail in any area of the picture smaller than the area of the 
photocell can not be transmitted. An electrical circuit is required 
to transmit information concerning the brightness of each ele- 
ment of picture area. As the amount of detail increases, the num- 
ber of electrical circuits increases. Such a multiple-circuit method 
is not practicable for transmitting images electrically over long dis- 
tances. A single channel must be employed for this purpose. This 
requires methods that involve dividing the light into elements, con- 
verting the illumination on each element into electrical impulses, 

-jen fc r/N<f con. s 
FIG. 2. Schematic arrangement of the Iconoscope 

transmitting these impulses in orderly sequence, and reconverting 
them into appropriately positioned light upon the viewing screen. 

In the RCA high-definition television system, the first step in this 
process occurs in the Iconoscope,* which converts the light-image 
into electrical impulses, and the final step takes place in the Kine- 
scope,* which transforms the electrical impulses into a light-image 
upon the viewing screen. 

The Iconoscope, illustrated in Fig. 2, consists of an electron gun 
and a photosensitive mosaic in a highly evacuated glass envelope. 
The electron gun produces a fine pencil or beam of electrons, which 
is focused to a spot on the mosaic. This beam is moved horizontally 

* Registered trade-marks of Radio Corporation of America. 



[J. S. M. P. E. 

and vertically, and so caused to scan the mosaic. The motion of the 
scanning beam is produced by appropriately applied electromagnetic 

The mosaic consists of a vast number of tiny electrically isolated 
photosensitized silver globules. These cover one side of a thin sheet 
of mica. The other side of the mica is covered with a conducting 
film, and this film is connected to a signal lead. The mosaic may be 
thought of as a very large number of minute photocells, each of them 
shunted by an electrical condenser which couples it to a common 
signal lead. When the mosaic is illuminated, these condensers are 
charged positively with respect to their equilibrium potential, due 

FIG. 3. The Iconoscope. 

to the emission of photoelectrons. This positive charge is pro- 
portional to the quantity of light received. The electron beam, as 
it scans the mosaic from left to right, drives to equilibrium the ele- 
ments over which it passes, and thus releases the charges and induces 
current impulses in the signal lead. The train of current impulses 
thus generated constitutes the picture signal output of the Iconoscope. 
These current impulses will appear in orderly sequence, as the electron 
beam scans the area of the mosaic one horizontal line at a time from 
top to bottom. It is in this order that the current impulses are trans- 
mitted as television signals. Fig. 3 is a photograph of a repre- 
sentative Iconoscope. 

In the Iconoscope the charging process in any specific element of 
of the mosaic continues for a time equal to the picture repetition in- 

Aug., 1937] 



terval; that is, until the beam, in the process, of scanning, returns to 
that element. The electrical charge stored in the condenser increases 
with this passage of time. The greater the electrical charge, the 
greater will be the current impulse induced in the signal lead. This 
storage principle makes the Iconoscope a very effective pick-up de- 
vice for television. 

The sensitivity of the Iconoscope is of great importance in picking 
up a wide variety of scenes, both indoors and out, under practical 
lighting conditions. This sensitivity at the present stage of develop- 
ment is about the same as that of ordinary negative film. Research 


FIG. 4. Color-response characteristic of the Iconoscope. 

in progress is disclosing methods by which it may be possible greatly 
to increase the sensitivity. 

The color-response of an Iconoscope depends upon the activation 
schedule used in producing the mosaic and upon the composition of 
the photosensitive material. The color-response characteristic may 
be varied over a range comparable with that covered by photographic 
emulsions available from motion picture work. The color-response 
characteristic of a representative Iconoscope is shown in Fig. 4. 

The Iconoscope and its associated optical parts correspond in the 
RCA television system to the camera in motion pictures. This unit 
of equipment is called the Iconoscope camera. Iconoscope cameras 
having the same elements but differing in physical form are used for 



[J. S. M. P. 

direct pick-up of indoor and outdoor scenes and for the transmissi< 
of motion picture film material. 

A photograph of an Iconoscope camera for use in indoor studic 
is shown as Fig. 5. The camera may be moved about the studit 
during a performance; it is raised and lowered by a motor-driver 
mechanism; the usual provisions are made for following the motior 

and action of the scene; it 
silent in operation. The Icono- 
scope mosaic is about 4 by 
inches, or about six times 
large as one 35-mm. motion 
picture frame. Therefore the 
Iconoscope camera lenses are of 
greater focal length than those 
employed in motion picture 
cameras. Present Iconoscope 
cameras are equipped with lenses 
of 6.5- or 18-inch focal length. 
Fig. 6 shows this camera, with 
the housing raised. The picture 
signals and the necessary power- 
supply currents are carried by a 
cable connecting the camera to 
the system. A wide-band pre- 
amplifier for amplifying the pic- 
ture signal produced by the 
Iconoscope is included in the 

The picture signals generated 
by the Iconoscope in the camera 
are amplified and delivered to 
the radio transmitter. These 
signals are caused to modulate the carrier-wave of the transmitter 
in a manner analogous to that employed in sound broadcasting. 
The radio signal thus produced is picked up at the distant point by 
the receiving antenna and delivered to the television receiver. Here 
it is restored to its original form as a train of impulses. These 
impulses are fed through amplifiers to the Kinescope, which trans- 
forms them into a light-image upon the viewing screen. 

The Kinescope is an evacuated glass envelope containing as the 

FIG. 5. Iconoscope camera. 



FIG. 6. Iconoscope camera, with the housing raised. 



[J. S. M. P. E. 

essential elements an electron gun and a luminescent screen. The 
electron gun produces an electron beam similar to, but of greater 

60 lines 

120 lines 

180 lines 

240 lines 


FIG. 7. Showing the improvement in detail with increasing numbers of 
scanning lines. 

current-carrying capacity, than the gun in the Iconoscope. Light is 
produced when the electron beam bombards the luminescent screen. 
The amount of light thus produced is proportional to the current 


in the beam. The electron beam is caused to scan the viewing 
screen by appropriately applied electromagnetic fields. 

The scanning beams in the Iconoscope and the Kinescope are ac- 
:urately synchronized. The two beams are at corresponding points 
jf the mosaic of the Iconoscope and of the luminescent screen of the 
Kinescope at any instant. The brightness of a point on the lumines- 
cent screen is proportional to the current in the bombarding beam. 
This current is produced by voltages related to the picture signals 
generated by the Iconoscope. These picture signals represent, by 
electrical impulses, information concerning the brightness of each 
picture element. Since the electron beams in the Iconoscope and 
Kinescope are in exact synchronism, the brightness of any point on 
the Kinescope screen will be a function of the brightness of the 
corresponding point on the mosaic of the Iconoscope. Thus the 
image projected upon the mosaic of the Iconoscope will be repro- 
duced with exactness upon the viewing screen of the Kinescope. 

The electron beams in the Iconoscope and the Kinescope are syn- 
chronized by transmitting synchronizing impulses at the end of each 
scanning line and at the end of each picture or frame. A synchro- 
nizing amplifier in the receiver separates the synchronizing signals 
from the composite signal by amplitude selection, separates horizon- 
tal and vertical synchronizing signals from each other by frequency 
selection, and delivers the impulses to the respective deflecting os- 
cillators in proper amplitude and polarity for synchronization. The 
requirement of accurate synchronization between the scanning beams 
at the transmitting and receiving ends of the circuit is one of the im- 
portant factors necessitating a uniform standard for all television 
systems to be used in broadcasting services in this country. 

As in motion pictures, the degree of technical perfection of the re- 
produced image may be measured in part by the detail it contains. 
To produce a system that will transmit and reproduce pictures of ac- 
ceptable detail has presented one of the most severe problems in 
television. The solution was found in the all-electronic system. 

The amount of detail that can be transmitted by a television sys- 
tem depends upon the number of picture elements resulting from 
the scanning process. The number of picture elements depends 
upon the number of lines by which a complete picture is scanned. A 
picture element has a height equal to the distance between the cen- 
ters of adjacent scanning lines; that is, the scanning-line pitch, 
and a length 56 per cent greater than its height, for equal hori- 



[J. S. M. P. E. 

zontal and vertical resolution in the picture. The number of picture 
elements, and hence the amount of detail, increases with the number 
of scanning lines. In a system that employs the Iconoscope and 
other electronic devices, the number of scanning lines, hence the pic- 
ture detail, may be greatly increased over that obtainable by earlier 
devices and methods. The Iconoscope mosaic does not limit the 
detail because many tiny photosensitive elements in the mosaic con- 
tribute to a single picture element. 

The detail that may be obtained by different numbers of scanning 
lines is indicated in Fig. 7. These are synthetic representations de- 

Photograph of a 441 -line television picture on the 
viewing screen of the Kinescope. 

veloped in the course of the studies of the subject. Pictures of less 
than 60 lines were used in early experimental systems. The elec- 
tronic system, embodying the Iconoscope and other electronic devices, 
produces pictures of satisfactory detail with 441 scanning lines. This 
amount of detail corresponds approximately to that obtained with 
16-mm. motion picture film. A photograph of an actual 441-line 
television picture is shown in Fig. 8. This is a photograph of an 
image on the viewing screen of the Kinescope. The picture was 
transmitted by the RCA system now under test in the New York 
City area. 

In television, as in motion pictures, two considerations are involved 


in determining the rate at which the scanning operation must be re- 
peated. The rate of repetition must be great enough to give the ap- 
pearance of reasonably continuous and natural motion in the repro- 
duced scene, and must be great enough to minimize unsteadiness or 
nicker in the reproduced picture. Continuity of motion is main- 
tained with a repetition rate of 16 pictures or frames per second. At 
least 48 frames per second are required, however, to minimize flicker 
unless some artifice be employed. Motion pictures are projected at 
the rate of 24 frames per second, and the artifice to reduce nicker 
takes the form of an additional blade upon the shutter that interrupts 
the light while the film is being pulled down from one frame to the 
next. Thus, as far as flicker is concerned, the projection is, in effect, 
at the rate of 48 frames per second. 

Such an artifice is not applicable in television. Some other method 
must be devised. Interlaced scanning is employed in the RCA sys- 
tem. This provides satisfactory freedom from flicker. In interlaced 
scanning, instead of scanning the picture in adjacent lines from top 
to bottom, alternate lines covering the entire area of the picture are 
first scanned, and then the beam returns and scans the omitted lines. 
The entire picture is scanned 30 times per second, but the picture 
area is covered in alternate lines 60 times per second. 

Another requirement for consideration in television is the relation 
that should exist between the frequency of the power supply to the 
transmitter and receiver and the repetition rate. It is desirable that 
the repetition rate be an integral divisor of the power-line frequency. 
This is necessary to minimize certain synchronous interference effects, 
which otherwise might be detrimental to the picture. The television 
transmitter and receivers of the RCA field test system operate on a 
60-cycle power supply. Hence a repetition rate of 30 frames per 
second fulfills the requirements. 

It should be noted that although the scanning beams of the Icono- 
scope and the Kinescope must be in exact synchronism, it is not nec- 
essary that the frequencies of the power supplies to the transmitter 
and the receiver be synchronous, that is, interconnected, provided 
they have the same nominal frequency and both systems are regulated 
in frequency accurately enough for the operation of electric clocks. 

The transmission electrically of high-definition images over a 
single channel requires very wide frequency band apparatus and 
circuits. This is occasioned by the rate at which information must 
be transmitted concerning the brightness of a very large number of 

132 R. R. BEAL \J. S. M. P. E. 

picture elements. A 441-line picture with an aspect ratio of 4 to 3, 
as transmitted by the RCA system, will contain 165,957 picture ele- 
ments, for equal resolution horizontally and vertically. This is de- 
rived from the product of the square of the number of scanning lines 
and the aspect ratio divided by 1.56, the dimension of the picture 
element in terms of the scanning line pitch. 

When 30 pictures per second are scanned information must be 
transmitted concerning the brightness of 30 times 165,957, or 4,987,- 
710 picture elements each second. One cycle of the picture signal 
provides such information for two picture elements; hence the total 
frequency band required for transmitting a picture as above described 
is about 2,500,000 cycles. 

This is the width of the frequency band that must be amplified and 
carried by the apparatus and circuits in the system. It is the fre- 
quency band by which the carrier-wave of the radio transmitter must 
be modulated. The total radio transmitting channel will be 5,000,- 
000 cps. when the carrier is modulated by the picture signal. This 
is equal to the combined widths of 500 sound broadcasting channels 
of 10,000 cycles each. 

Channels of such great width are not available in the frequency 
spectrum now used for radio services. For this and other reasons 
related to technical requirements, the ultra-high frequencies, or 
ultra-short waves, are used for television. Frequencies above 30 
megacycles (X < 10 meters) are employed. Ultra-short waves have 
quasi-optical properties in propagation. The range over which satis- 
factory high-definition television pictures may be reliably transmitted 
by ultra-short waves is limited practically to the distance of the horizon 
from the height at which the transmitting antenna is placed. Under 
some abnormal conditions, pictures may be received over greater 
distances for periods of very short duration, but primarily television 
stations will serve local areas. The signals from the stations in these 
local areas will be stable and will have about the same intensity dur- 
ing the day and night hours, and during the seasons of the year. 

Television networks for the simultaneous distribution of programs 
originating at one point will consist of interconnected local stations. 
The circuits interconnecting these stations must be capable of trans- 
mitting the very wide frequency band required for high-definition 
television. Existing circuits, either wire or radio, can not fulfill 
this requirement. New facilities must be provided ; and while wide 
frequency band circuits, either cable or radio, are feasible technically, 


to provide them for extensive, nation-wide networks become an 
economic problem of magnitude. 

The development of a high-definition television system has re- 
quired technical advances over a broad front. Fundamental re- 
search in an unexplored portion of the radio-frequency spectrum was 
required to determine the laws of propagation of ultra-short waves 
and to produce methods and devices by which they may be applied. 
Entirely new methods and apparatus had to be produced for picking 
up images and converting them into electrical impulses for transmis- 
sion. New methods and devices were required for amplifying, trans- 
mitting, and receiving the very wide frequency bands on ultra-short 
waves. The fundamental character of the work and its extensiveness 
constitute practically the development of a new art. 

The technical advances made through a step-by-step program of 
research in the laboratory, and through practical tests in the field, 
have been incorporated in the television system RCA now has under 
experimental test in the New York City area. 

The equipment provided for this field test is installed under con- 
ditions that closely correspond to the requirements of a television 
broadcasting service. The field tests are comprehensive in scope. 
They embrace studies of the functioning of the equipment under 
field conditions; the collecting of engineering information and data 
related to signal and noise levels within the service area; experiments 
to develop program technic; and observations on receivers in the 
field by technical personnel. 

This system is now using standards of which the essentials are 
441-lines per frame, a frame frequency of 30 per second, a field fre- 
quency of 60 per second (interlaced), negative polarity of transmis- 
sion, and a video-audio (picture-sound) carrier-frequency spacing of 
3.25 megacycles. The picture signals are transmitted on a frequency 
of 49.5, and the sound at a frequency of 52.75 megacycles. 

The studios in which artists perform and from which motion pic- 
ture film is transmitted are located in the RCA Building, Radio City 
(New York). The radio transmitting equipment is installed in the 
Empire State Building, and the transmitting antenna on top of the 
building. The picture signals from the Radio City studios are sent 
to the radio transmitter in the Empire State Building either by co- 
axial cable or by ultra-short-wave radio relay. The accompanying 
high-fidelity sound is carried over special cable circuits. 

The terminal equipment at Radio City includes three Iconoscope 



[J. S. M. P. 

FIG. 9. Radio City television studio. 

FIG. 10. Studio control room. 



FIG. 11. Film projector equipment. 

FIG. 12. Film studio control room. 



[J. S. M. P. 

Cameras for direct pick-up in the artists' studio and two motioi 
picture film projectors of special design, each with its Iconoscoi 
camera. This equipment includes the video, or picture signal, am- 
plifiers, and the deflecting and control apparatus for each Iconoscope 
camera, the Kinescope monitors, the synchronizing generators, the 
line amplifiers, and other associated apparatus. 

FIG. 13. Synchronizing generator and video line amplifier 

Television Studio. The equipment in the Radio City television 
studio is shown in Fig. 9 as it is used for a program transmission. In the 
scene shown in the photograph, the Iconoscope cameras are employed 
to pick up scenes to be transmitted in sequence by switching from 
one camera to the other. The switching operation takes place in 
the studio control room, which is located in an elevated position at 
one end of the studio. The sound that accompanies the picture is 
picked up by a standard velocity microphone equipped with a wind- 
shield and attached to a boom. 


The studio is about 30 by 50 feet, with a ceiling height of about 18 
feet. It is an NBC studio formerly used for sound broadcasting. 
The studio is equipped with incandescent lamps of various types, 
having a total power consumption of more than 50 kw. The lighting 
equipment is flexible, to enable comprehensive studies of a variety of 
effects in experimental programs. Rifles, floods, and focusing spots, 
with ratings between 2 and 5 kw. each, are most numerous, although 
there are several large units of special design. Key lighting and 

FIG. 14. Inter-building ultra-short-wave radio relay 

back-lighting units are suspended from the ceiling; modelling lights 
are operated on the studio floor. The present sensitivity of the 
Iconoscope requires an incident light-intensity upon a set of about 
1000 to 2000 foot-candles. 

Studio Control Room. Adjoining the studio and at such an elevation 
that the operating engineers have a clear view of the studio scene, is 
the studio control room. This control room is shown in Fig. 10. 
The sound and video signals from the studio are monitored in this 
room. The scenes are picked up by the Iconoscope camera and re- 
produced on the two monitoring Kinescopes shown at the left of the 


[J. S. M. P. E. 

FIG. 15. Empire State Building control panel. 

FIG. 16. Empire State Building video and audio transmitters. 


photograph. One monitor shows the scene 'being transmitted, and 
the other the scene picked up by the second Iconoscope camera pre- 
paratory to transmission. The operating position in the foreground 
of the photograph controls the sound from the studio. The video 
controls are at the opposite end of the control board. The racks of 
equipment behind the engineers include the video amplifiers and the 
synchronizing and control equipment associated with each Icono- 
scope camera. 

Film Studio. Motion picture film material originates in a film studio 
in another part of the National Broadcasting Company plant. This 
studio consists of two rooms, in one of which are installed two special 
35-mm. motion picture projectors and other supplementary equip- 
ment, and in the other two Iconoscope cameras with video and 
monitoring and control apparatus. The projectors are so designed 
that standard 24-frame motion picture film is used to produce tele- 
vision pictures at 30 frames per second. In these projectors a chang- 
ing rate of intermittent drive is used for the picture portion of the 
film and a constant 24-frame rate of feed for the sound portion. Pic- 
tures from the projectors are focused on the mosaics of the Iconoscope 
cameras located in the same control room beyond the partition sepa- 
rating the two rooms. The film projector equipment is shown in 
Fig. 11. 

Film Studio Control Room. A control room is associated with the 
film projection room. A view of this room is shown in Fig. 12. The 
equipment in the film studio control room includes two Iconoscope 
cameras with their video voltage amplifiers and associated synchro- 
nizing and control equipment, and audio equipment for the con- 
trol of the sound from the film. The two Iconoscope cameras are 
so mounted that they may be shifted from side to side for use with 
either of the film projectors in the adjacent room. 

Synchronizing Generator and Line Amplifier Equipment. The panels 
containing the electronic synchronizing generator equipment, and 
the video line amplifiers that feed the video signal to the Empire 
State Building are shown in Fig. 13. This equipment is installed in 
the main equipment room of the National Broadcasting Company 

Inter-Building Transmission. The inter-building ultra-short-wave 
radio relay transmitter (Fig. 14) is installed on the 10th floor of the 
RCA Building. It operates on a frequency of 177 megacycles, and 
has a channel width adequate to carry the full video frequency band. 

140 R. R. BEAL [J. S. M. P. E. 

Equipment is provided for monitoring the signal at this point. The 
transmission distance between the two buildings is approximately 
0.9 mile. The signal obtained at the Empire State Building is free 
from noise, and pictures transferred by radio relay are as satisfactory 
as those for which the coaxial cable is used. 

Empire State Building Control Panel. The coaxial cable and radio 
relay channels, and the channel for the sound accompanying the pic- 
ture from the studios in Radio City terminate at the Empire State 
Building control board (Fig. 15). From left to right, the control 
board consists of the sound channel panel, a video monitoring panel, 
the radio relay receiver panel and battery and switching panels. 
The video monitor may be switched either to the radio relay or the 
coaxial cable channel. 

Transmitters. The video and audio transmitters installed in the 
Empire State Building are shown in Fig. 16. The video and audio 
transmitters are entirely separate, and are specially designed for 
high-power operation on ultra-high frequencies. The modulator of 
the video transmitter is capable of handling the wide side-bands re- 
quired for the video frequencies. Both transmitters are coupled to 
a common transmission line connected to the single antenna on top 
of the building. 

Antenna. This antenna produces a horizontally polarized field with 
a pattern essentially circular in the horizontal plane. The antenna 
has a power gain in the horizontal plane of about 2.1, or 3.2 db., 
as measured with reference to a vertical dipole. The Empire State 
Building, having a height of the order of 1250 feet, provides a loca- 
tion from which a maximum transmitting range may be obtained. 
The distance from the antenna to the horizon is approximately 43 
miles. Fig. 17 shows a view of the Empire State Building transmit- 
ting antenna. 

Experimental Field Test Receivers. The experimental field test re- 
ceivers resemble in appearance a console broadcast receiver. Fig. 18 
is a photograph of the type of receiver now in use. This re- 
ceiver is of the superheterodyne type, and has a tuning range 
of 40 to 84 megacycles. It receives the picture and the sound. 
The Kinescope is mounted vertically and the television image 
is viewed in the mirror mounted inside the cover of the cabinet. 
Tuning is accomplished by a single knob controlling the radio- 
frequency circuit and the single oscillator which heterodynes both 
carriers to produce two intermediate frequencies. 

Aug., 1937] 



Of the seven knobs on the front of the receiver the center knob 
tunes the picture and the accompanying sound. The three 
knobs on the right, from top to bottom, are the sound volume 
control, the treble tone control, and the bass tone control. The 

three knobs on the left, from 
top to bottom, are the picture 
contrast control, the detail con- 
trol, and the background bright- 
ness control. These receivers 
operate on the ordinary 110- 
volt, 60-cycle power supply, and 
draw about 350 watts of power. 
These receivers have been 
used to produce two sizes of 
pictures. For the first few 
months of the tests, the picture 
size was 5 l /t by 7Va inches. At 
the present time most of the 
receivers have Kinescopes that 
produce pictures 7 l /z by 10 
inches in size. Fig. 18 shows a 
9-inch Kinescope that produces 
a 5 l /t by 7 1 / 2 -inch picture. A 
Kinescope about 12 y 2 inches in 
diameter is required to produce a 
7 l /z by 10-inch picture. The 
shape of the picture, defined by 
the aspect ratio 4 to 3, is the same as that used in motion picture 

The brightness of the reproduced picture is such that it can be 
viewed in a moderately lighted room. The color of the Kinescope 
screen depends upon the composition of the fluorescent materials. 
Many screen colors have been produced. At the present time a 
slightly greenish yellow screen and a more nearly white screen are 
being used. The present yellow screen used for the 7 x /2 by 10- 
inch picture has a brightness in the highlights of about 4 foot-lam- 
berts. This may be compared with the tentatively proposed stand- 
ards of 7 to 14 foot-lamberts for the brightness of motion picture 
theater screens. 
The optimal viewing distance for a 441-line picture of the 7 l /z by 

FIG. 17. Transmitting antenna on 
tower of Empire State Building. 



[J. S. M. P. E. 

10-inch size is of the order of three to four feet. At this distance the 
line structure is not resolved by the eye. The screen angle or the 
angle subtended by the picture at the eye is about 20 degrees. At a 
viewing distance of 12 feet, the screen angle is about 5 degrees, which, 
in general, is of the order of magnitude of the minimal acceptable 
screen angle for motion pictures. The size and brightness of the 7 l /z 

FIG. 18. Experimental field test receiver. 

by 10-inch picture of 441 lines appears to satisfy reasonably the re- 
quirements for pictures to be viewed in the home by the average 
family group 

In connection with television program technic, it is too early to 
predict accurately the technic that ultimately will develop in tele- 
vision programming. It is clear to those who are closely associated 
in the development of a system that although some parts of the pro- 


gram technic may parallel the technics of the stage, motion pictures, 
and sound broadcasting, it will be distinct from any of these. In 
effect, a new art form must be created. 

In general, television program material may fall under three prin- 
cipal classifications. These are direct pick-ups from indoor studios 
and other points, outdoor pick-ups, and motion picture film. Spon- 
taneity eventually may be an important element in television pro- 
gramming. The televising of outdoor events as they occur is en- 
tirely feasible under the light conditions that prevail during fair 
weather. Studio programs and motion picture film probably will 
find liberal use in television programming, but here again the re- 
quirements peculiar to television will affect the nature and composi- 
tion of the material. 

The field tests in the New York City area are contributing to fur- 
ther technical advances. Pictures of 441 -scanning lines have been 
transmitted and satisfactorily received within a service area having 
a radius of 30 miles or more from the Empire State Building. Good 
pictures are regularly received at one observing point in a suburban 
home over a distance of 45 miles. 

Much remains to be done. When it will be completed can not be 
accurately predicted. The engineering information and data col- 
lected and the experience gained from operating the system under 
field conditions are pointing the way toward the realization ulti- 
mately of a high-definition television broadcasting service. 

This new service, just as have many new services in the past, will 
supplement and not supplant the existing services or agencies rep- 
resenting the older arts. The telephone did not supplant the tele- 
graph; it supplemented it. Sound broadcasting did not supplant 
the theater and the motion picture. On the contrary, it increased 
public interest and appeal in them, and thereby contributed to their 
advancement and financial profit. And so it will be with television. 
When it is successfully accomplished, we shall have added another 
service to the continually growing list. There will be some things 
that television can do that previous arts can not do; a few things 
that it can do better than they; but there will be many things that 
they will continue to do that television can not do. We may there- 
fore welcome the advent of a great new public service, which will 
come not to displace but to augment our agencies of entertainment 
and information, thereby making the world a more interesting place 
in which to live. 


Summary. This report supplements the report of May 15, 1936, of the Scientific 
Committee of the Research Council of the Academy of Motion Picture Arts & Sciences. 
Developments since the appearance of the first report are traced briefly, specific refer- 
ence being made to the recent British experiment and other developments abroad, as 
well as to the field-tests now being conducted in America. 

The Research Council's first report on the status of television was 
released on May 15, 1936. * This, the second announcement on the 
subject, is therefore a review of a full year's progress in this field. 

The members of the reporting committee are too well aware of both 
the potentialities and uncertainties of technological research to claim 
infallibility for such predictions as their task entails. It happens, 
however, that only one of the forecasts contained in the 1936 report 
requires, as yet, any essential modification. In every other particu- 
lar the 1936 report is as valid now as when it was issued. To quote 
from that report, it is still improbable that television will burst on an 
unprepared motion picture industry; many millions of dollars must be 
invested before nation-wide urban exploitation of television becomes 
possible in the United States ; the start of such a development, fore- 
cast for 1937-38, is confirmed; television service for rural areas is 
still beyond the calculable future. The one change to which we would 
call attention is that recent improvements in the design of electronic 
projection devices give promise of a considerable enlargement of tele- 
vision screen area, the realization of which would vastly accelerate the 
evolution of television as a practical art. 


It is legitimately claimed for the transmissions inaugurated from 
the Alexandria Palace in London, on November 2, 1936, that they 
constitute the first and only existing public television service. For 
this achievement the British Broadcasting Company, the Marconi- 
Electrical Musical Industries, the receiver manufacturers, and the 

* Reprinted from Technical Bulletin (June 15/1937) of the Research Council 
of the Academy of Motion Picture Arts & Sciences, Hollywood, Calif. 



other governmental and private interests involved deserve the credit 
due to pioneers in a difficult field. Looked at realistically, however, 
theirs is still an experiment, as is any enterprise in which more prob- 
lems are raised than solved. 

The accomplishments may be summed up as follows : 

(1) Regular transmissions for two hours a day over a period of seven months, 
using an all-electronic system with 405 lines and 50 pictures a second, interlaced. 

(2) The sale of not over 1000 television receivers in a highly populous area 
within, roughly, a 60-mile radius from the transmitter. 

(3) The development of technic and operating organization, including multi- 
camera pick-up, studio procedure, special effects, training of personnel, accumula- 
tion of engineering data, etc. 

(4) As a special event, the televising of the Coronation procession, under ad- 
verse weather conditions, to some thousands of viewers. 

Our correspondents in England agree, however, on the following 
adverse conclusions: 

(1) The received pictures, which are of the order of 7 1 / 2 by 10 inches, are too 
small to afford more than scant entertainment value, even if other technical diffi- 
culties, such as a consistent lack of definition in the longer shots, are overcome in 
due course. 

(2) The cost of the receivers, 60 and 80 pounds ($297 and $396 at the present 
rate of exchange) makes television a toy of the well-to-do. 

(3) The theatrical content of the video broadcasts has rarely risen above the 
level of mediocrity. 

In short, the picture is small, the cost high, the show poor, and the 
patronage meager. Even allowing for the success of the Coronation 
visual broadcast, we have to date an entertainment tour de force, 
rather than a spontaneous growth in answer to a genuine public de- 
mand. As for the economic question, it is no nearer solution than 
when the experiment was inaugurated. It is argued that if larger 
governmental subsidies can be secured, better shows will become 
available, and eventually wide-spread public interest and participa- 
tion can be enlisted. Perhaps so. In the United States a few thou- 
sand radio amateurs listened to the Highbridge audio broadcasts in 
1916; a few years later the number of broadcast listeners had risen 
into the millions. In the case of British television it is too early to 
draw conclusions. At the moment one can say only that such an 
efflorescence is a hope rather than an early probability. By the end 
of the year there should be signs of a healthy impetus from within, or 
the enterprise will begin to have the appearance of that languishing 
type that needs interminable injections of outside aid. 



In Germany there is considerable television activity. Scenes froi 
the Olympic Games were televised, but apparently the results wei 
unimpressive. In France the forthcoming installation of a 30-kilo- 
watt transmitter on the Eiffel Tower is announced. There are als 
reports of Russian purchases of television equipment in the Unite 


In the United States the active television interests have accepted 
the Radio Manufacturers Association standard of 441 lines, a frame 
frequency of 30 pictures a second, a field frequency of 60 pictures a 
second, interlaced, and an aspect ratio of 4:3, the same as in motion 
pictures. These are the present characteristics of the test trans- 
missions by the National Broadcasting Company from the Empire 
State Tower in New York, which are the nearest American equivalent 
to the British operations reviewed above. (The former, however, is 
not a public service; the receivers, of which there are over one hun- 
dred, being in the hands of RCA executives and engineers who report 
confidentially on the results.) The shows originate in a special 
studio in the RCA Building and are relayed to the transmitter over a 
coaxial cable and a radio link between the two buildings, whose air- 
line separation is under one mile. The power of the transmitter, 7.5 
kilowatts, is sufficient to lay down a satisfactory signal on the optical 
horizon, which is some 43 miles from the top of the 1250-foot tower. 

The size of the received pictures is about the same as in the British 
case: 7 l /z by 10 inches. Such a picture is afforded by a 12 l /2-inch 
cathode-ray tube, a size readily manufactured in the present state of 
the art. 

This experimental service has been in operation for about eleven 
months, with an interval to permit changing the transmitter from the 
earlier 343-line standard to 441 lines, and some briefer interruptions. 
A mass of data on the technic of televising, electrical interference con- 
ditions, signal distribution, etc., has been and is being collected. Pa- 
pers describing the technical aspects of the research are presented peri- 
odically before the Society of Motion Picture Engineers, the Institute 
of Radio Engineers, and other recognized bodies. In connection 
with one of the most recent of these papers there was a demonstration 
on a scale as large as 10 by 8 feet, using optical projection from a Kine- 
scope equipped with a suitable lens system, with, it is said, impressive 


results. (Similar experiments have been carried on in Germany, but 
there it was reported that the optical quality of the larger pictures 
was unsatisfactory.) 

Occasional television programs are transmitted from a Philco 
station in Philadelphia, and others. The Columbia Broadcasting 
System has announced its intention of installing a television trans- 
mitter on the Chrysler Tower in New York. 


Both here and abroad, systematic engineering progress is being 
made in the development of high-definition television. The situation 
has reached a point where it warrants careful observation and analy- 
sis. Just as the physical equipment required can not be brought 
into existence quickly, it is impossible to acquire a background in a 
field as complex as television overnight, and study well in advance is 
a prerequisite of wise and economical planning. The time is not far 
off when those engaged in motion picture production, and others 
whose interests are likely to be affected by the evolution of this new 
field, will do well to acquire as much familiarity as possible with its 
characteristics and methods. 

We recur to the question of picture size. As soon as larger pictures 
are available with the requisite photographic quality, television 
may be expected to gain marked impetus, and commercial appli- 
cation in the larger urban centers will not be long delayed. The 
lesson to be derived from the British experience to date may be that 
when those in a position to gauge entertainment value advise that a 
given picture size is inadequate for successful commercial application 
no purpose is served by trying it out on the public. The likelihood of 
a favorable verdict does not increase with the size of the jury. For 
the United States it is to be hoped that no attempt will be made to commer- 
cialize home television until a picture equivalent in definition to the best 
home-movie projection, and not smaller than 24 by 18 inches, can be 
furnished with routine reliability. The most important interests in the 
domestic field appear to be committed to some such prudent policy. 


New York and Los Angeles together constitute the principal reser- 
voirs of movie, radio, and television talent in this country. It may be 
expected, therefore, that when the problems of providing television 
service for the New York area are well on the way to solution, say, in 


1938 or early 1939, the next major urban area selected for television 
coverage will be that of Los Angeles. The topographical and physical 
conditions in the two regions are quite different, and, it would appear, 
are on the whole more favorable in the West. 

In New York the land elevations are relatively low, no point in any 
of the five boroughs, excepting Staten Island, being as high as 300 feet 
above sea level. To secure short-wave coverage, therefore, it is neces- 
sary to radiate from high buildings, of which there is no scarcity. 
However, the mass of steel structures on Manhattan Island of neces- 
sity casts radio shadows that complicate the problem of television dis- 

Los Angeles, in contrast, is a city of low structures, but natural 
elevations provide numerous sites from which television service could 
be effectively provided. Cahuenga Peak, for example, with an alti- 
tude of 1825 feet, affords an eminence about 50 per cent again as 
high as the Empire State Tower, commanding the San Fernando Valley 
to the north, the greater part of Los Angeles to the south and east, 
and the beach cities to the west. Topographically, as well as from 
the aspect of talent availability and entertainment facilities, Los 
Angeles is a favorable site for a television center. 


In view of the progress being made in television, this Committee 
feels it advisable to report its findings semi-annually hereafter, and is 
scheduling its work accordingly. The next report will thus be issued 
in January, 1938. 

CARL DREHER, Chairman 





1 "Television from the Standpoint of the Motion Picture Industry," Technical 
Bulletin (May 18, 1936), Academy of Motion Picture Arts & Sciences; reprinted 
/. Soc. Mot. Pict. Eng., XXVI (July, 1936), No. 1, p. 74. 


Summary. Revised drawings for most of the standards, except those on sound 
sprockets, have been prepared and are to appear in a forthcoming issue of the Journal. 

There have been no fundamental changes except with regard to the sound-film. For 
35-mm. film, the dimensions of the sound-track have been changed; and for 16-mm. 
sound-film, similar changes have been made and the distance between the picture and 
the corresponding sound has been changed to 26 frames. 

Inasmuch as the revision of the standards drawings being prepared 
by the Committe will be published in an early issue of the JOURNAL, 
they will not be given at this time. Most of the changes have to do 
solely with tolerances and with improved forms for showing the 
essential dimensions. 

New Drawings. The most important actual change recommended 
is an increase in the width of the variable-width sound record on 
35-mm. film from 0.071 inch to 0.076 inch. The latter value is actu- 
ally in use now, and was introduced to make room for the double 
track for the push-pull recording system. This change involves also 
a change in the sound-track dimensions for 16-mm. film to allow for 
reduction printing. The width of the sound record is increased from 
0.060 inch to 0.064 inch. The width of the printed area for the 
variable-width sound-track has been reduced, however, from 0.096 to 
0.085 inch so that the printed area for both types of sound records 
is the same. 

Screen Brightness. In accordance with the recommendation of the 
Projection Screen Brightness Committee and its endorsement by the 
Projection Practice Committee, the Standards Committee is propos- 
ing to adopt as recommended practice a standard screen brightness 
of not less than 7 or more than 14 foot-lamberts. There have been 
some good arguments against this recommendation, and further 
comments will be welcomed before the final adoption of this recom- 

Standard Densities. After investigation by the Sub-Committee to 
determine the possibility of standard densities for standardizing den- 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received May 
20, 1937. 




sitometers, the recommendation has been approved by the Standards 
Committee that strips of photographic film standardized by reference 
to an integrating-sphere densitometer be used as reference standards. 
In spite of the fact that these densities are not permanent, it is be- 
lieved that they are as permanent as any other densities likely to be 
obtained, and have the further advantage of offering approximately 
the same degree of light-scattering as the photographic film with 
which they are to be compared. 

16- Mm. Spools for Projection Reels. In spite of the fact that in 
Europe it appears likely that a standard reel for educational sub- 
standard film will be adopted with square holes on each side, the 
Standards Committee here has voted to adopt the recommendation 
of the Committee on Non -Theatrical Equipment that all such reels 
be built with a round hole on one side and a square hole on the other. 




E. K. CARVER, Chairman 








Summary. A brief account of new accessions to the SMPE motion picture exhibit 
at the Los Angeles Museum, and a description of two new galleries added to the dis- 
play facilities. 

The Historical Committee has been active in collecting relics, 
memorabilia, and data concerning the past as well as the present of 
the industry and its personalities, so that complete records may be 
preserved in the SMPE exhibit at the Los Angeles Museum. 

The historical exhibit and files have been of considerable help to 
authors preparing books on cinematic subjects, a number of authors 
having used the museum data in some of their publications. 

A second gallery has recently been added to increase the display 
facilities at the Los Angeles Museum. In it are being exhibited 
paraphernalia and material illustrating many of the advances of 
cinematic science. The gallery serves a two-fold purpose: first, as 
the "Science of Motion Picture Production Gallery," it tends to give 
the visitors some knowledge of the functions of various studio de- 
partments in film production; second, it encourages engineers and 
inventors to make available apparatus and documents of their 
achievements for preservation. It is particularly desirable that 
exhibits representative of all phases of motion picture production be 
submitted. The gallery already includes displays illustrating many 
phases of motion picture making. One such exhibit covers the proc- 
ess of designing a set. In the latter display, chronologically ar- 
ranged, are material illustrating the various steps taken in designing a 
setting from a manuscript, drawings ranging from the conceptual 
sketches of the art department to those of the final model, and photo- 
graphs of the completed set. 

Another exhibit includes equipment showing in a popular manner 
how sound is recorded. In this display are records made of soft wax, 
light-valves, tubes used in sound systems, paraphernalia for special 
sound effects, and other devices, as well as some historical relics. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received May 
24, 1937. 



Illumination and set lighting are demonstrated by devices and photo- 
graphs. The application of color to motion picture film is illustrated 
by drawings and objective material. A prop department, recon- 
structed to represent a cross-section of a typical movie-prop depart- 
ment, has been built in one section of the gallery. Noted props and 
materials used for dressing sets of outstanding films make up the 
prop display. 

In addition to the technical material and in order to make the 
gallery as comprehensive as possible, exhibits showing how films are 
publicized and campaigned are also included. 

Space is available in the gallery for displaying all significant ma- 
terial. Material may be submitted on a temporary loan basis, al- 
though outright presentation is preferred so that the records and 
equipment may be regarded as permanent. 

In the historical gallery the work of bringing together the memor- 
abilia and relics has gone forward, and much new material has been 
added during the past year. An animated cartoon display using 
original drawings and score-sheets from cartoon films made by Walt 
Disney, the Harmon-Ising Co., and Walter Lantz illustrates the film- 
ing and departmental procedure in production. A case of original 
background paintings and drawings of cartoon characters from the 
representative producers of today has been added to the display. Ma- 
terial from cartoon films that have won awards and attracted much 
public attention has also been acquired and is on display. 

Mr. J. R. Bray has made available a group of photographic enlarge- 
ments from his first cartoon, The Artist's Dream, released on June 
12, 1913, from which the entertainment possibilities of the cartoon 
film first became apparent, and the popularity of this form of cine- 
matic medium first became evident. There were, of course, earlier 
cartoons, such as those made by Vitagraph as early as 1906. 

Many catalogues of manufacturers of motion picture equipment 
have been acquired, dating back as far as 1898. This kind of material 
is valuable to research students who wish to investigate the progress 
of the industry. 

A number of relics portraying the pioneer attempts to produce 
animated pictures have been obtained. One such relic is a motion 
picture of twelve exposures, with a single pin-hole between each frame 
instead of perforations for advancing the film. The pin-hole perfora- 
tions are reinforced. Each frame is about-3V2 inches square. It was 
made by E. H. Amet on a piece of kodak roll film, and judging from 



the general texture of the celluloid and from, comparisons with other 
films, the 40-inch motion picture was made about 1894-95. Many 
other exhibits have been received, including early cameras, projectors, 
and other materials. 

The Committee has been bringing together biographical records for 
publication and for future reference, and anyone having documents or 
records of pioneering activities is invited to submit the material 
for consideration. 

To help preserve the relics of the motion picture industry, the 
membership of the Society is invited to send material and documents 
to the Los Angeles Museum for preservation, for depositing or on either 
a loan or gift basis. Cards crediting the donor with the gift or loan, 
and outlining the history of the piece are attached to the exhibits in 
the display gallery. 


E. THEISEN, Chairman 



Summary. A brief account of the plan followed by the Committee in constructing 
and arranging Convention programs. 

A year ago this Committee initiated the plan of publishing in the 
JOURNAL abstracts of the papers and Committee reports to be pre- 
sented at the Semi-Annual Conventions. This plan has been fol- 
lowed for three consecutive meetings, the material being published 
each time in the issue of the JOURNAL appearing several weeks prior 
to the Convention. Abstracts of approximately eighty-five per 
cent of the papers and reports for these three meetings have been 
published, and it is believed that the publication of these abstracts 
has aroused greater interest in the meetings, helped to increase the 
attendance, and facilitated the discussions. 

In our April, 1936, report a proposal was made that the program of 
the next Convention should be prepared as follows: (a) publication 
of a request for papers in the issue of the JOURNAL published five 
months before the meeting and in each succeeding number prior to 
the meeting; (b) personal solicitation of papers on subjects of current 
interest; (c) assignment of preferred positions, with ample time for 
presentation and discussion, to the best papers submitted up to 
approximately five weeks before the meeting; (d) balancing the re- 
mainder of the program by adding papers as submitted up to about 
three weeks before the meeting. An attempt was made also to obtain 
a manuscript of each paper before it was read at the Convention. 

A fair response to this plan was realized, but the number of manu- 
scripts turned in by the date specified was not as great as had been 
expected. The bulk of the preliminary program material was ob- 
tained finally by urgent solicitation during the last week before it had 
to be released for printing. Manuscripts were obtained, however, for 
90 per cent of the papers. 

At the open forum, which was held at the Rochester Convention 
on Friday afternoon (Oct. 15, 1936), comment was made that our 

* Presented at the Spring, 1937, Convention at Hollywood, Calif. ; received May 
13, 1937. 


programs were too crowded with papers, and that insufficient time 
was allowed for discussion. It is very difficult to know exactly how 
much time to assign to a paper, because the ability of authors to 
present their papers in a condensed but clear manner varies consid- 
erably. Each author has been urged to rehearse his presentation, 
but we fear that very few authors do so. 

The Committee well realizes the importance of intelligent dis- 
cussion, but we wish to point out to the membership that, in addition 
to a Convention program, the Society also publishes a monthly 
JOURNAL. The papers read at the Semi-Annual Conventions com- 
prise 95 per cent of the material for this JOURNAL. We have nearly 
1400 members distributed throughout the world. Of the 1400 it 
must be remembered that perhaps 1000 never get to our meetings. 
Those members depend upon the JOURNAL as their source of informa- 
tion, and, in fairness to them, it is very important that the present 
size of the JOURNAL be maintained. 

The editorial office has been faced twice during the past year with 
an acute shortage of material for several issues of the JOURNAL, which 
has been alleviated only by vigorous efforts by this Committee and 
the Board of Editors. A healthier situation would be to have on 
hand more material than is required, from which the best could be 
selected for publication. 

Although the number of papers submitted for publication only 
(not read at the Convention) has increased slightly in recent years, 
the stimulus of attendance at a Convention is apparently necessary 
to get the majority of authors to write papers for the JOURNAL. 

It is of interest to note that 32 of the 35 papers read at the 1936 
Spring Meeting, and 30 of the 34 papers read at the 1936 Fall Con- 
vention, have been published. These figures indicate, however, that 
very little material was on hand on May 1, 1937, for the July, 1937, 
issue, and how necessary it is that manuscripts for each meeting be 
turned in to the Committee before each meeting. 

To remedy this situation and alleviate somewhat this shortage of 
material, the Papers Committee urgently requested in January that 
the Board of Governors approve a five-day Convention in May, 1937. 
This was done, and with the cooperation of a special local section of 
the Committee we have been able to arrange a well balanced program. 

For discussion of the technical papers, 25 per cent of the total time 
allotted is intended for discussion, and 50 per cent of the total time 
for apparatus papers. It is believed that, with the full cooperation 



of the authors and of those who take part in the discussions, the pro- 
gram will go forward as scheduled. 


G. E. MATTHEWS, Cltairman 





Local Papers Committee 

W. A. MUELLER, Chairman 
L. A. AICHOLTZ, Secretary 





Summary. The lighting of motion pictures is discussed with relation to a new 
lechnic developed by the author and employed in several recent productions, notably 
"Anthony Adverse" and "The Life of Emile Zola." 

The use of artificial lighting for motion picture scenes originated with attempts to 
imitate the flat overall illumination produced by daylight on the early "daylight" 
stages. When the concepts of modelling and effect lighting were introduced, they 
were regarded merely as adjuncts to an overall flat general lighting. They have, in 
the main, so continued until today, despite the great advances made in optics and 
sensitive materials. 

The author holds that under modern conditions, this lechnic is faulty. He has 
therefore dispensed with the so-called "general lighting," and has for some time done 
all his lighting with various types of spotlighting units. This enables him to light 
more precisely; to accommodate his effects and his equipment to the physical require- 
ments of modern production technic; and to achieve more natural effects upon the 

The lighting of motion pictures is an outstanding example of the 
way the creative artists who work actually on the sets are linked to 
the creative engineers who work behind the scenes developing im- 
proved equipment and materials for their use. Each improvement in 
tools or materials makes it possible to evolve new and better tech- 
nics for using them. 

Within the past few years two such improvements have been 
brought out. The film manufacturers have provided faster, more 
delicately sensitive emulsions. The lamp manufacturers have pro- 
duced more precisely controllable lighting units. 

The result, in the writer's case, at least, has been the development 
of a new and more precise method of lighting, which has been proved 
in actual use on such productions as Anthony Adverse and The Life of 
Emile Zola. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
May 24, 1937. 

** Warner Bros. -First National Studios, Burbank, Calif. 




[J. S. M. P. E. 

In order to understand any new development, it is always a good 
idea to glance backward to see what has gone before. Often it makes 
it easier to see why things evolve as they do. The earliest motion 
pictures were all illuminated by natural light, whether the scene 
represented an exterior or an interior. The reason for that was 
simple: thirty or forty years ago even the best emulsions were 
painfully slow; and lenses, judged by present-day standards, were 
even slower. An aperture of //4.5 was regarded as the acme of speed; 

FIG. 1. Scene from The Story of Entile Zola, showing the effect of spotlight- 
ing through the skylight. 

many cine* lenses worked at still smaller openings. Emulsions had 
an H&D speed of less than 400, compared to present-day speeds of 
1000. At the same time, cin exposures had to be made at an average 
shutter-speed of Veo second or less. 

Clearly, the sun was the only light-source of sufficient intensity to 
make an exposure possible under such conditions. 

It is true that some fairly powerful artificial light-sources existed 
in those days, but using them in quantities sufficient to illuminate 
even a tiny set was generally economically impossible for the early 
producers, many of whom had virtually exhausted their capital in 
buying or leasing a single camera and a scant supply of film. 


So, for many years, motion picture scenes exterior and interior 
alike were illuminated solely by sunlight. Some of the earliest 
studios were simply the flat roofs of office buildings, with the sets 
made of "flats" of painted canvas hung against the walls of adjoining, 
higher buildings. 

Later, as the film business prospered, studios were erected especially 
for motion picture making. These were at first simply unroofed, un- 
walled floors over which intricate systems of muslin curtains were 

FIG. 2. Scene from The Story of Emile Zola, in which the set and charac- 
ters are lighted almost entirely by spots. 

stretched to diffuse the light. Later, glass-paned roofs and walls 
were added to make the stages weather-proof. In consequence of 
these conditions, the ideal lighting of the period was simply a flat, 
even flood of light throughout the set. No attempts at modelling or 
light-effects were possible, or even thought of. 

Inevitably, as the business grew further, the fact that a company 
could not work when the weather was bad became an economic hin- 
drance. This was specially noticeable in the East, where production 
was then centered, and where the weather can be cloudy and stormy 
for days and weeks at a time. The answer to that was the intro- 

160 G. GAUDIO [J. s. M. P. E. 

duction of artificial lighting. Perhaps the studios could not afford 
the new expense; but they could afford still less to let their releases 
wait on the weather. 

So the earliest use of artificial lighting was nothing more than a 
matter of substituting a powerful artificial illuminant for the sun. 
There were two principal types of lamps used at that time. There 
were the "Aristo" arc lamps, adapted probably from street-lighting 
service, and the Cooper-Hewitt mercury-vapor tubes. Whichever 
type was used, the lamps were permanently fixed in place, being 
usually swung on chains or rigid supports from the roof of the stage. 
In many installations the lamps represented fixed units, and the sets 
were built beneath to conform to the lighting. Ultimately, similar 
floodlighting units, both arc and vapor-tube, were mounted on stands 
and used on the floor beside the camera, to light the sets from the 

The result, of course, was simply a flat, fairly even flood of light 
throughout the set. No modelling was thought of ; very little would 
have been possible, anyway, since only floodlights were available. 

Moreover, in many instances any departure from a fixed scheme of 
flat lighting was frowned upon. Back in 1913 or 1914, when I was 
photographing The House of Discord, with Blanche Sweet, Lionel 
Barrymore, and Marshall Neilan, at the old Biograph Studio on 
175th Street, in New York, I very nearly lost my job because I tried 
to reproduce the glow cast from a fireplace. As late as 1915 or 1916 
my fellow-cameraman David Abel, who is responsible for the dis- 
tinguished photography of the Fred Astaire successes, was dismissed 
by a studio for the unheard-of crime of shining a spotlight through a 
window to create the effect of a beam of sunlight! 

However, the demand for such natural effects, and the then newly 
discovered value of back-lighting to separate the actors from their 
backgrounds, ultimately brought about the introduction of spot- 
lighting equipment. The condensing-lens spotlight was borrowed 
from the stage. Later, as sets grew larger and more intense beams 
were needed, the mirror spotlight was borrowed from searchlighting 
service. With these tools at hand, lighting took on a new aspect. As 
time went on, it was learned that lighting could make or mar the ap- 
pearance of the players; that it could model their forms and faces; 
and that it could give an illusion of depth and solidity to the setting. 

Still, be it understood, this use of lighting was merely in addition to 
a flat overall lighting which provides the illumination for the ex- 


posure. Wherever sunlight alone could serve, it was made to do so. 
This was especially true here in California, where the climate was the 
original attraction to the industry. Nevertheless, even here the use 
of sunlight for illuminating interior scenes slowly but surely gave way 
to the use of artificial light. Yet it was not until we were well into 
the 1920's that the glass walls of the last "daylight" stages were 
opaqued out, and only within the last two years did the last open 
stage in use (at the Chaplin studio) make way for a closed sound stage. 

During those years, successive improvements were made in film and 
lenses, as well as in the usable apertures of camera shutters. Film 
speeds increased to 600, 800, and 1000, H&D; lens speeds increased 
to//3.5, f/2.7, and beyond. Shutter apertures widened from 90 and 
120 degrees to 170 or 180. Such advances made it possible to use 
less light and to alter negative development procedure to give a 
softer, more pleasing negative. Each advance made corresponding 
changes in the lighting technic. 

About ten years ago came two sudden changes, almost together, 
which altered the entire conception of lighting. These were the 
introduction of panchromatic film and the coming of sound. Pan- 
chromatic film had been available for some time before any of us 
in the studios dared to try it. It is one thing to try a new product 
for oneself, and quite another thing to risk an employer's investment 
of hundreds of thousands of dollars on something so radically different 
as was panchromatic film. But one by one we tried the new film, and 
were convinced. I believe I used it on the first big production to be 
photographed entirely on "pan" when I photographed Hell's Angels. 

With panchromatic film, the softer, yellower light of the incan- 
descent or Mazda type of lamp was more satisfactory than the hard , 
blue light of the arc. Most cinematographers rather preferred to use 
the arcs, however, for they were more accustomed to them. 

Then came sound. As soon as the microphone joined the troupe, 
the early arcs had to go, because the sizzling noise made by them 
was recorded on the film. Whether we wanted to or not, we had to 
change to the quieter Mazdas. 

Personally, I think I was lucky in that respect, for I had had the 
privilege of making many of the Mazda lighting tests filmed in the 
Hollywood-Roosevelt Hotel by the American Society of Cinema- 
tographers, the Academy of Motion Picture Arts & Sciences, and the 
Producers' Association. Changing to Mazdas on production was 
not such a problem. 

162 G. GAUDIO [J. s. M. p. 

Actually, the change to Mazda lighting did not change thinj 
fundamentally. The basic principles of lighting remained unchanj 
Where formerly we had had arc floodlights, condensing-lens ai 
spotlights, and mirror-arc spotlights, with some mercury-vapor tut 
we now had incandescent floodlights, incandescent condensing-ler 
spotlights, incandescent mirror spotlights, and incandescent overhe 
floodlighting strip units. Once we knew how they and the fih 
worked together, we could and did use them almost exactly as 
had used their arc counterparts. 

Meanwhile, two new factors appeared. Emulsions grew steadily 
more and more sensitive, progressing through Type // panchromatic 
through Supersensitive to today's Super-^T. And the directors dis 
covered that the slower-paced talkie could be speeded up by having 
the camera move about the set. 

Inevitably, these developments influenced lighting. As film 
came faster, it became possible to use lower levels of illuminatioi 
When that happened, we discovered that it was necessary to contr 
our lighting with greater precision. Uncontrolled beams of spille 
light straying from the spotlighting units, which formerly had beet 
too faint to make any impression upon the film, now picked up em- 

With the modern directorial technic, the camera, instead of beii 
statically set up to photograph a fixed combination of lighting anc 
action, moves about the set continually. Every inch it move 
changes its relation to the lighting. Consequently a set has to 
lighted so as to appear right, not merely in relation to one viewpoint 
but to perhaps a dozen viewpoints. 

The first approach to these problems, and one still used by soi 
cinematographers, is to flatten the lighting as much as possible, anc 
get a good, conservative general illumination, with as much modellii 
as they feel is safe. That, however, often tends to involve the use 
more light than is necessary, and complicates the lighting set-uj 
It sometimes, too, requires the use of a lot of floor units, which make 
the manipulation of the camera-carriage or boom more difficult. 

This method, to me, is attacking the problem wrongly. It cer- 
tainly does not allow us to make full use of the materials and technics 
at hand. We have camera equipment that can travel all over the 
set, unless impeded by a maze of lamps and lamp-cables. We have 
a film that is so sensitive that we can use less light than ever before. 
We have spotlighting units, like the new Solarspots, which project 


the light more efficiently than anything with which we previously had 
to work. 

Why not make use of these advantages? 

During the past year, this thought kept returning to my mind with 
every scene I photographed. I experimented a bit more on each 
succeeding picture until the technic used in Anthony Adverse was 
fully developed. 

It might be termed "precision lighting," because it is achieved 
almost exclusively with precision lighting tools spotlights. General 
floodlighting, formerly used to assure a safe exposure-level of illu- 
mination over all, is no longer needed or used. Instead, every detail 
of both actors and set is illuminated by light-beams projected from 
spotlights. There is no difference in the amount of light used, but 
since every beam can be controlled precisely, there is a tremendous 
improvement in the result on the screen. 

Our normal concept of light is that it comes from above. Outdoors 
even on a cloudy day, the light comes from the sky above us. Indoors 
in the daytime, the light comes through the windows on a downward 
slant; at night, most of our artificial lighting fixtures cast their rays 
from a position generally above eye level. Why, then, in photo- 
graphing a motion picture should we play our light on sets and actors 
from any angle but above ? 

It is true that lighting actors from above may cause shadows under 
the eyebrows, chins, and so on. At least it would if we illuminated 
the actors with but one concentrated beam. But in practice, we 
almost never light a player so crudely. No matter what effect we 
may be seeking, or what method of lighting we use, we light each 
actor with several beams, of various intensities, spread, and diffusion, 
and from several different directions. With all these beams we can 
either wipe the shadows completely out, or turn them to advantage 
in giving naturally modelled, three-dimensional effects. 

Therefore, if any of you should visit a set where I am making a 
picture, you would find that all my lighting units are spotlights, ar- 
ranged on the lamp-rails above the set. Only in rare instances is it 
necessary to use lamps on the floor. Sometimes there may be an 
inaccessible corner of a set that can be illuminated only by a beam 
projected from a lamp placed upon the floor; sometimes, also, in 
making close-ups it will be more convenient to use a lamp or two on 
the floor for front-lighting. But normally there will not be a single 
unit of any kind on the floor. All the lighting is done with spot- 



[J. S. M. P. 

lighting units condensing-lens spotlights, mirror spotlights, and the 
new Fresnel-lensed Solarspots. 

There is another precision lighting tool that plays a big part in m] 
lighting the dimmer. When the electricians are getting the lamj 
ready for rigging a set for me, they know that floodlighting equipment 
will not be needed, but rather four to half a dozen or more smal 
dimmers. I can then re-balance the lighting by bringing this unit 
up or that one down, as the players or the camera move about the 

For instance, in Zola there is a scene played in an artist's studic 
overlooking Paris. The far wall of the set consisted almost entirely 
of broad windows and skylights. Now in real life, in such a room, 
all the illumination would come from the windows, so I illuminated 
my set in that manner. A series of spotlights on the lamp-rail above 
the set projected beams down through the skylight and the window. 
From the opposite rail, just enough diffused light was projected to 
relieve the shadows caused by this strong key -lighting, and to prevent 
the scene from being an absolute silhouette. These two angles of 
light were carefully balanced to produce a natural effect. 

This lighting balance was not, however, enough to show up an 
actor's facial expression if that was important, as it was in one part 
of the scene. Here is where the dimmers played their part. For 
good part of the scene, Muni played with his back to the camera, 
looking out through the windows. Thus far, the lighting was satis- 
factory. But a little later he had to turn and face the camera, to speak 
an important line to a friend inside the room. The lighting balance 
was no longer dramatically correct, for while the semi-silhouette 
effect was precisely what the eye would actually see in such a room, 
there was not enough front-light to show clearly the facial expressions. 
If a big dimmer had been used to raise the intensity of all the front- 
light, the effect would have been unnatural. So I used a smaller 
dimmer, wired into the circuits of only the lamps focused upon the 
one player. Normally, the lamps might be turned very low, or even 
completely out. As Muni started to turn, the dimmer was slowly 
operated to bring the intensity of the lamps up to the correct level. 
When he turned away again, the lamps were dimmed again. Often 
there are four or five dimmers on a set, each coupled to but one or 
two spotlights, and the electricians will work the dimmers up and 
down as the action requires. Sometimes a simple scene may have a 
dozen dimmer changes. 


There are a number of ways of building lighting. Some begin with 
a general flood of flat, overall illumination sufficient to assure a safe 
minimum exposure-level. Others key the lighting plan to the high- 
lights, often counting on spilled light to illuminate the shadows satis- 
factorily, and filling in with diffused spotlights and floodlights when 
additional general illumination may be needed. 

The writer's method is to begin by planning for the shadow -areas, 
and build them up to the desired level with spotlight-beams. And 
here is an important fact : in nature there is normally no such thing 
as an opaque shadow. Even the darkest shadows ordinarily en- 
countered reflect a little light, so that at least a suggestion of some- 
thing can be seen. We may not penetrate the shadow enough to 
make out all the details, but we can almost always get an idea of what 
is in the shadow. 

In photography, things are different. If a shadow does not reflect 
enough light to make some sort of exposure on the film, the picture 
will show merely an opaque, jet-black emptiness where the shadow 
is. On the other hand, if we throw too much light into the area, there 
is simply no shadow at all. 

That is why I begin with lighting the shadows. Since our most 
modern lighting units emit little or no spilled light, rays from them 
are not to be counted upon to keep the shadows transparent. Ac- 
cordingly each shadow is illuminated to the exact level required in the 
completed lighting. From the shadows it is a natural progression up 
through the middle tones to the highlights. 

There is a natural focal highlight in every scene, which almost al- 
ways coincides with the center of interest of the scene. Just as an 
art director, when making a perspective drawing of a set, starts his 
pencil at some focal point and draws the basic lines of his sketch so as 
to radiate from that point, so should the cinematographer's lighting 
radiate from this natural focal highlight-point in his scene. There 
may be, and almost always are, secondary principal highlights, but 
they should be distributed with pleasing relationship to this main cen- 
ter of interest and light. 

Establishing motion picture lighting in this manner, and from this 
viewpoint permits, even compels, the use of more natural lighting 
effects. For instance, suppose that I am seated in a room at a desk. 
A desk-light creates a strong focal highlight where I sit. Farther 
down the room is an open window, through which the light from the 
outside establishes a secondary highlight-area. If I rise from the 

166 G. GAUDIO [J. s. M. P. 

desk and walk to the window, I would pass through the shaded arc 
and enter the area of the secondary highlight. 

Ordinary set-lighting technic would do one of two things : It woulc 
either create the two highlight-areas and leave a dark, almost opaque 
shadow between them, or it would illuminate the whole room brightly, 
making little or no distinction between the highlight-areas by the 
desk and the window and the surrounding and naturally shaded 
areas. In one case, as I arose from the desk I should disappear into 
the shadow and then emerge from it into the other highlight by the 
window. In the other, I should be equally visible and probably 
equally well lighted all the way from one position to the other. 

I have been trying to light my scenes during the past year so that 
the result would be more closely akin to what the eye sees in life. 
Seated at the desk, I would be in the principal highlight-area, fully 
illuminated and modelled. So, too, would I be illuminated when stand- 
ing at the window. The lighting would be so arranged that the illu- 
mination would fall off gradually, as it would in actuality, as I moved 
away from the desk-lamp; and then slowly increase again as I ap- 
proached the light from the window. The audience would be aware 
that I had moved out of the sphere of one light-source into that of an- 
other. I would not be unnaturally illuminated as I crossed the room ; 
neither would I vanish into pitch-black shadow. If the lighting that 
produced the proper effect when I was not standing in one of the prin- 
cipal light centers should not produce the required modelling of my 
form when I was standing in one or the other position, additional 
spotlighting units could be brought up with dimmers as I approached, 
and dimmed again as I left. Properly done, this change in lighting 
would not be evident as a change upon the screen. 

The same technic can be used just as well for moving-camera shots, 
for following an actor in his movements about the room. In fact, it 
enhances the effectiveness of such shots and strengthens the impres- 
sion of moving about with the player. One does not, if he is walking 
through an average room with another person, expect to see the per- 
son always perfectly illuminated as he moves from the region of one 
light or window to that of another. Why, then, should it be so s 
in a picture? 

In both of my most recent productions, Anthony Adverse and 
Zola, most of the moving-camera shots have been lighted so as to 
simulate natural effects, letting the players move through the less 
brilliantly lighted areas, and concentrating the highlights and the 


modelling effects in what would in actuality be the logical highlight- 
areas. I try, of course, to make those points coincide with the dra- 
matically important parts of the scene, and especially with the spots 
where the characters stand still for any length of time. The result 
upon the screen is more convincingly natural, and both audiences and 
critics have accepted the results very favorably. 

The scene in White Angel in which Kay Francis, as Florence 
Nightingale, walks, candle in hand, through the long hospital wards 
at night ministering to the wounded soldiers, was lighted in such a 
manner, the lighting that played upon her at each stopping point 
being controlled by dimmers. 

From this discussion it will be seen that this form of lighting must 
of necessity be very closely interlocked with the composition of the 
scene, just as it should be, for composition is really much more than 
the mere geometrical arrangement of lines, masses, and objects. 
Composition should properly take into consideration lighting; and 
lighting, composition. The best composition can be ruined by in- 
correct lighting. Technically excellent lighting can be bad if it is 
not properly coordinated with the composition. The two are, in 
fact, so closely related that, as one of my colleagues once remarked, 
"If you light the scene properly, the composition is half made; if you 
begin by composing the scene properly, and light accordingly, the 
lighting is half made before you touch a single lamp." 

The technic described here requires neither more angles of illu- 
mination nor more lighting units than the conventional general- 
lighting-plus-spotlighting technic. Far from requiring a higher level 
of illumination, it permits, as a rule, the use of lower levels. It en- 
ables the cameraman to take more complete advantage of today's 
films, lenses, and lamps. It greatly simplifies both the lighting and 
the photographing of modern moving-camera scenes. 

It must be admitted that this kind of precision lighting is not, and 
can not be, so routine as the more conventional methods of lighting. 
It can not be hurried through carelessly, or by roughly applying a 
set formula. It definitely requires that the director of photography 
be alert at all times. But the results upon the screen are immensely 
more satisfying, not alone in that they can be more artistic, but that 
they become more natural; and naturalness is the elusive element 
that all of us most earnestly strive to reproduce upon the screen. 

168 G. GAUDIO 


MR. MORGAN: Are polarized screens being used for dimming? 

MR. GAUDIO: They are applied more to exteriors, where there is considerable 
reflection of light ; but not to interiors. 

MR. MORGAN: What method do you use for dimming the lights? 

MR. GUADIO: We use the set of dimmers, as explained in the paper. We mark 
the dimmer so that when the actor turns around the intensity is greater than 
it was when his back was toward the camera. The dimmers turn with the same 
speed as the actor and when his face is toward the camera it will be lighted in good 
balance instead of being a black silhouette. 

Referring to the example mentioned in the paper, the window was no farther 
from the actor in either instance. If I had used a flare light on the face, the wall 
beneath the window would have been flooded with light. The depth and the 
apparent distance of the actor from the back wall would have been lacking. Six 
or eight spots covering the area including the face would keep the wall at the same 
intensity as when the actor had his back to the camera. 

MR. MORGAN : What method of testing do you use? 

MR. GAUDIO: Sometimes I use a photoelectric meter. The cameraman may 
not need a meter for small sets, of which he has previously made other pictures; 
but whenever I am in doubt, I make the tests in cooperation with the laboratory 
or the camera department. 

MR. HAWKINS: For television we have equipment that is comparable to the 
old insensitive film. We require strong back lighting so that the characters will 
stand out from the background. Do you recommend the old overhead high- 
level illumination, or could we use your method of lighting? 

MR. GAUDIO: I am quite ignorant of the technic of television, but speaking 
photographically, if you need very strong light to bring out the actors pronounc- 
edly I suggest that you use the high level. There is no objection to doing so. With 
a strong spotlight you can get all the intensity you want, and build up the face, 
and the background will remain unchanged. If the front is built up with flood- 
lights, the background will also be in the floodlight. I eliminate the floodlights 
from the floor because with them I can not control the depth as well as I can with 
the spots. 

MR. LUBCKE : Is your lighting different for different types of films? 

MR. GAUDIO : No. You heard Fred Jackman's paper : On account of the screen 
reflection, Mr. Jackman does not use floodlights. Spots do not interfere with 
the background but provide the quality and the density, and the highlights and 
the shadows. 

Of course, sometimes, different quality is required: You would not want the 
same lighting effects in a comedy as you would in a dramatic production. How- 
ever, last year, when making The King and the Chorus Girl I did not change any of 
the technic at all, except as to the brilliance. Light comedy requires more bril- 
liance than does a picture like the Life of Louis Pasteur, but the routine technic 
is exactly the same. 



Summary. Within the past several months the technic of lighting Technicolor 
motion pictures has changed from more or less flat, evenly illuminated sets of high- 
light level to a method whereby the cinematographer now uses a much lower level of 
general illumination and has greater freedom with the use of "modelling" lamps. 

Recent developments in arc lamps for use in Technicolor lighting are discussed. 
The changed technic of lighting, made possible by the new equipment and the labora- 
tory advancements, is briefly explained. The uses of each type of illuminant, diffu- 
sion screens, black screens, and other lighting-control devices are described. An 
explanation is given of the part taken by the chief set electrician, or "gaffer" in 
lighting motion picture sets. 

A previous paper 1 described the studio illuminating equipment used 
for Technicolor productions in 1935. Since that time developments 
in arc lamps and changes in the Technicolor process have occurred 
that represent considerable advances in the technic of Technicolor 

The last report of the Studio Lighting Committee 2 gives the aver- 
age light-intensity used on black-and-white sets as 250 to 400 foot- 
candles, and on Technicolor sets as 800 to 1000 foot-candles. Dur- 
ing the past year Technicolor has been able to reduce the illumination 
by more than 40 per cent, and in some cases to approximately the 
same levels as now used for a great deal of black-and-white work. 
These changes have been made possible by the use of more efficient 
lighting equipment, changes in the Technicolor photographic technic, 
and advances in the art of laboratory processing. 

When the first Technicolor three-color picture was made the MR-29 
twin-arc broadside and the MR-27 Scoop 3 were the only modern arc 
lamps available. These lamps were developed for general illumina- 
tion in Technicolor photography, and were placed around and above 
the set in such a manner as to establish a uniform overall illumination. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
May 4, 1937. 
** National Carbon Co., Cleveland, Ohio. 




[J. S. M. P. E. 

The spotlamps and Sun arcs used for creating areas of higher inten- 
sity, such as through doors and windows, back-lighting, streak- 
lighting, etc., were lamps that had been used for many years on black- 
and-white productions. Although they delivered more light on the 
set than the scoop or broadside, they did not give as even a field, nor 
were they as quiet, or as good in color quality. Therefore, the broad- 
side and scoop were used wherever possible. As a result of these 

conditions a great many more lamps 
were used on the sets than would have 
been necessary if modern high-intensity 
equipment had been available. 


One of the new lamps recently de- 
veloped to meet Technicolor's needs 4 is 
shown in Fig. 1. Figs. 2, 3, and 4 show 
the light distributions of the new units 
in comparison with the distribution of 
the old type 36-inch Sun arc shown in 
Fig. 5. The decided advantages of the 
new lamps from the standpoint of uni- 
formity of field, intensity, and beam 
control are quite apparent. 

The MR Type 90 lamp is now used in 
place of the older 80-ampere rotary 
spot. 1 Although the two units are of 
approximately the same size and weight, 
the Type 90 at a beam-spread of 40 
degrees delivers more than three times 
the light of the 80-ampere rotary, and 
at a beam-spread of 16 degrees twelve 

Concentric plano-convex lenses made of circular prisms are used in 
the new lamps, with the arc crater facing the lenses so as to eliminate 
all shadows of the lamp parts. With the old-style 36-inch Sun arc 
(Fig. 5), the drop in illumination at the center of the field is caused by 
the shadow of the positive head in the beam reflected by the mirror. 
The 36-inch Sun arc is still used where a deep penetration of light is 
desired on particularly long throws, or where very sharp shadows are 

FIG. 1. One of the new 
lamps developed for Tech- 
nicolor productions. 



FIG. 2. 

FIG. 3. 

FIG. 4. 

FIG. 5. 

FIGS. 2, 3, and 4. Light distribution curves of new units. 
FIG. 5. Light distribution curves of old type 36-inch Sun arc. 



(J. S. M. P. 


The spectral distribution of the radiant energy from the mo tic 
picture studio carbons 1 used in the broadsides and scoops is such that 
no filters are used unless certain special color effects are desired. 
With the high-intensity carbons used in the spotlamps and Sun arcs, 
however, the radiant energy in the blue and near-ultraviolet portions 
of the spectrum is too great for proper color balance. Therefore, a 
straw-colored gelatin filter is used in front of each of these units. 

Here again Technicolor has effected a saving in light, since, by the 
use of non-fugitive dyes, they have succeeded in producing a gelatin 
that does not fade and whose transmission can therefore be relied 



U-ra. H.I. Hegatir* 
150 jnpr*s, 81 Tolta 4-. 

13.6-ou H.I. 

7/16 .. Orotip 

185 Ampra, 63 Volts d-. 

. High-Low Posltlr* 

5/16 o.. Orotip NegatiT* 
70 Aarper*8, 49 Tolta d-e, 

I I I 


Angstrom Unit* 



FIG. 6. Spectral energy distribution curves of high-intensity carbons 
through YI filter (positive crater radiation only). 

upon. It was necessary to judge by eye the transmission of the first 
unstable gelatin filters each time they were placed in use, and it was 
common practice for that reason to use double thicknesses on certain 
lamps as a matter of protection. Fig. 6 shows the spectral energy 
distributions 9f the high-intensity arcs with the special straw YI 
filter, as employed in the lamps. 


Improvements in the laboratory processing of the film, details of 
which are outside the scope of this paper, have made it possible to 
change the illumination technic from that of more or less flat lighting 
with a uniform overall light intensity, to an advanced color technic 
with widely varying levels. The new technic allows the cinematog- 

Aug., 1937] 































E * 













<N <M 












i i 




t i 






O 1C 



1 1 





^ CD 
























s * 



. bo 





<f> 4> 










ed by Technical 





D 'tn 
*~7 O 
^ PH 

o . 

G "^ 




.ti u 

S 55 

o -^ 

.0 _> 

"3 s, 

~ bo 
03 4i 


'I o 

o o 



Mazda Lamp 

for modelling, 

nee throws or i 








E ^ 

X 55 














g X 

C*! \ 

E x 

CO \ 

E E 
E E 

CO --H 



































t i 






"bo t 










^ o 

J3 o 

^ "o 







4> C 

> " 

41 C 
> C 

> s 







S "S 






o rt 

a >> 







Twin vert 
Solenoid i 








mination w 

vhere great 


o " 



^ >- 





o< *^ 



-. 41 

ctf ho 

















D^ ft^ 







o * 

S-^ ^M 








^ { 










[J. S. M. P. 

rapher to use ari abundance of modelling light, reducing the int 
in the shadow areas, and thereby effecting a further saving in light. 
The unrestricted use of modelling lamps of suitable intensities has 
given the color cinematographer the same tools that are used in black- 
and-white work, and the cinematographer 's artistry is not hampered 
by technical limitations. 

In preparation for lighting a motion picture set, a conference is 
usually held between the cinematographer and the chief set electri- 

FIG. 7. A scene from Vogues of 1938, showing the lighting equipment used 
at the present time. (Courtesy Walter Wanger Productions.) 

cian. In deciding upon the general level of illumination the cinema- 
tographer considers the speed of the photographic equipment, the 
requirements of the producer and director, the mood of the story, the 
color of the set, and many other remote factors, all of which makes of 
him an artist rather than a technician. 

The chief set electrician or "gaffer" is the lighting technician on 
the set. He directs the placing and control of equipment up to the 
point where artistry enters. He knows from experience what each 
lamp will deliver, where it is best used, and the number of units re- 
quired for a given effect. If he has worked with the cinematographer 


previously he is usually able to establish the positions of all general 

As a result of his conference with the cinematographer the set 
electrician orders lamps to be placed upon the floor, behind doors and 
windows, and on parallels constructed around the walls of the set. 
When he has finished "roughing in" the lighting equipment the set 
is illuminated in such a manner that it could be photographed without 
change and a technically satisfactory negative would result. 

Now the cinematographer takes charge. He orders frosted gela- 

FIG. 8. A scene from Kid Millions, an early Technicolor three-color se- 
quence, showing the lighting equipment used at that time. (Courtesy Sam 
Goldwyn Productions.) 

tin or silk screens placed over certain lamps to reduce the intensity and 
to diffuse the light emitted from them. In other areas he raises the 
light-intensity by adding more lamps or by reducing the beam-spread 
of the units already in place. Other lamps are moved to stations 
where they will better establish the effect he desires. Black screens, 
called "gobos," are set at various points to keep the light from reach- 
ing places where it is not desired or where it may interfere with the 
free movement of the actors. He establishes points of deepest 
shadows and brightest highlights. Between these points he manipu- 
lates the equipment until the set is "modelled" into an area of high- 



[J. S. M. p. 

lights, middletones, and shadows that blend with the mood of tt 

Because the lighting of a motion picture set is often a compromise 
between the cinematographer's desire for a given effect and the 
limitations of the equipment and process, it is difficult to attempt to 
state the number of lamps required for any given area. Table I 
lists the types of equipment used by Technicolor; Table II details 
the various units used in photographing the huge ballroom set of 
Becky Sharp, Technicolor's first three-color feature picture. The 
quantity of equipment used was based upon an estimate given by 
Ray Rennahan, chief cinematographer for the picture. Table II 


Comparison of Quantity of Lighting Equipment 

Lamp Equipment Used on 
Becky Sharp Ballroom Set 


36* Sun Arcs 19 

24* Sun Arcs 47 
100-amp. Rotaries 4 

80-amp. Rotary Spots 87 
35-amp. Spots 1 

Broadsides Type M-R29 71 

Scoops MR-27 78 

MR Junior Spots 12 
36* Sun Spots 9 

24* Sun Spots 5 

18* Sun Spots 5 

Rifles 5 

Domes 1 

Strips 40 

Corresponding Equipment That Would 

Be Used under Present 
Lighting and Photographic Conditions 

Quantity Quantity New Type 

Total Lamps 



30 MR-150's 
40 MR- 90's 

Total Lamps 

12,895 Amps. 

Generator Load at 115 Volts 20,000 Amps. 

also shows Mr. Rennahan's estimate of the lamp equipment 
would be required for the same set under present conditions of light- 
ing. The reduction from the earlier requirements is apparent. 
Figs. 7 and 8 also illustrate the difference. 

According to William V. Skall, Technicolor cinematographer, a 
further saving of light has been made possible because the new lamps 
afford better control. Figs. 2, 3, and 4 show that these new units emit 


a very even field of illumination at various divergences. The slopes 
of the curves occur where the light from one lamp overlaps that from 
another, thereby making it possible to balance the light in any desired 
area with a minimum use of silks, jellies, or gobos, to cut down or 
block out undesired light. 

William Howard Greene, Technicolor cinematographer, states that 
at the present time there is very little difference between lighting a 
Technicolor set or a black-and-white set. The cinematographer now 
has the freedom of black-and-white with the additional advantages of 
depth and beauty that natural color affords. 


1 HANDLEY, C. W.: "Lighting for Technicolor Motion Pictures," /. Soc. 
Mot. Pict. Eng., XXV (Nov., 1935), No. 5, p. 423. 

2 Report of Studio Lighting Committee: J. Soc. Mot. Pict. Eng., XXVIII 
(Jan., 1937), No. 1, p. 32. 

3 MOLE, P.: "New Developments in Carbon Arc Lighting," /. Soc. Mot. 
Pict. En&., XXH (Jan., 1934), No. 2, p. 51. 

4 RICHARDSON, E. C.: "Recent Developments in High-Intensity Arc Spot 
lamps for Motion Picture Production," /. Soc. Mot. Pict. Eng., XXVIII (Feb., 
1937), No. 2, p. 206. 




Summary. The basic principles of motion picture set lighting are outlined, 
the technic of "key" lighting, employed by most cinematographers, is discussed. 

Several new types of lamps that have found extensive use are described in detail. 
Technical data regarding them are presented along with information regarding their 
application in cinematography. 

Any discussion of motion picture set lighting should be prefaced by 
acknowledging the fact that modern lighting is in practice susceptible 
of almost infinite variation. One could go into any studio, and, con- 
sidering the work of two equally prominent cinematographers, find 
that although the two undoubtedly base their technic upon similar 
principles, use the same tools, and obtain very similar results upon 
the screen, their detailed methods as measured by the quantity of 
light used, the number of units, and the way in which the lighting is 
balanced, would differ greatly. 

It is therefore manifestly impossible to set up a fixed rule and say 
that, for a set of given size, so many foot-candles from each direction, 
making such and such a total, will be required. Such a formula could 
be devised, perhaps; but it would deal simply with illumination not 
with lighting, as it is understood and practiced here. 

In previous discussions of the evolution of motion picture lighting, 
it has frequently been pointed out that the modern lighting technic 
evolved, bit by bit, from the very early necessity for a sufficient in- 
tensity of illumination to permit an exposure. It was found, as soon 
as artificial light-sources began to supplement the less controllable 
natural illumination, that projecting beams of light upon sets and 
actors from a variety of angles could give improved effects of depth 
and roundness to the picture. The development of lighting from 
that time has been closely interlocked with the development of light- 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
May 20, 1937. 

** Mole-Richardson, Inc., Hollywood, Calif. 



projectors affording more precise control of these beams. A similarly 
important factor has been the introduction from time to time of more 
highly sensitive emulsions, permitting a decrease in the overall illu- 
mination level and making more precise control of the intensity and 
divergence of light-beams desirable. 

This is very well illustrated by comparing the so-called "general" 
lighting of a few years ago with current practice. This phase of 
lighting, as the name implies, deals with the maintenance of a defi- 
nite overall level of illumination throughout the set. Until relatively 
recently this was most generally achieved by means of the so-called 
"general lighting units" the broadside, the "rifle," the multiple- 
unit "bank" and overhead "scoops" and "strips." The primary 
function of these units was to establish a uniform overall flood of light 
covering a vertical and horizontal spread of sixty or more degrees. 
These units, especially the broads and rifles, mounted upon pedestals 
on the stage floor, were arranged uniformly in rows on each side of 
the camera. Sometimes such lamps would also be positioned upon 
the lamp-rails at the tops of the sets. In the case of deep sets which 
could not easily be penetrated by the floor units, in instances where 
particularly high levels of illumination were desired, as in earlier 
color processes and in black-and-white musical revue numbers, addi- 
tional general lighting was commonly provided by scoop and strip 
.units suspended above the set. 

This general lighting provided foundations of even, diffused illu- 
mination throughout the sets, even in the deepest shadows. The 
necessary intermediate tones and highlights were built up from this 
by means of more intense beams projected by the spotlighting units. 

Within the past year, however, this rather characterless overall 
lighting has been definitely on the wane. Today, we have reached 
a point at which it can be said that this kind of lighting is definitely 
on the way out. A number of factors have contributed to the change. 
For one thing, we have put behind us the early-talkie technic of using 
a multiplicity of cameras on every scene; and, through experience, 
cinematographers have learned how to light moving-camera shots 
more normally than was at first deemed necessary. Second, new 
materials and still faster, emulsions have made flat foundational light- 
ing more and more unnecessary, while the development of new and 
more accurately controllable light-projecting units has made it 
easier to light sets with precision. 

There has, moreover, been noticed a new conception of the whole 

180 E. C. RICHARDSON [j. s. M. p. E. 

problem of set-lighting. Not so long ago and especially in the five 
or six years immediately following the introduction of sound, which 
for a time seemed to set cinematography back immeasurably a set 
was to a surprising extent viewed more nearly as something to be 
illuminated than as something to be lighted. It had, in other words, 
merely to serve as an acceptable background for the characters, rather 
than to take its part as an integral part of the composition. 

During the past few years, the concept has changed. It is no longer 
enough merely to light the set to give some illusion of depth, and to 
keep it in accord with the visual mood of the action. It must now be 
lighted decoratively, as an important part of the composition. More 
than a few of the industry's outstanding cinematographers have stated 
that they lavish quite as much care upon lighting the set itself as 
upon lighting the star actors. 

Several well recognized means take care of creating the illusions of 
depth and roundness. Depth, for instance, is most frequently 
achieved by contrasting the illumination of various planes of the 
scene. A relatively dark foreground can be more or less silhouetted 
against a more strongly illuminated middle plane, beyond which the 
next plane may be either darker or lighter, and so on. Generally 
speaking, the plane in which the object or action of greatest interest 
lies will be the most strongly illuminated, since the more highly 
keyed lighting concentrates the attention upon that plane. 

The illusion of roundness is achieved by highlighting curved sur- 
faces with little catch-lights which give to the single eye of the : 
camera something of the effect they give to normal binocular vision. 
Modelling flat and angular surfaces is accomplished by contrasting 
halftones of light. Protrusions and indentations in wall areas, for j 
example, are not illuminated flatly, but in such a manner that there 
are unobtrusive but still definite shadows that render the objects in 
pseudo-relief upon the screen. These effects are most generally at- ; 
tained with projecting or spotlighting units, mounted overhead, and 
usually "crossed" ; that is, an object on the left of the camera will be 
modelled by a beam striking it angularly from a lamp on the right of 
the camera, and vice versa. At times, too, a beam may be played ver- 
tically down the wall of a set from a lamp mounted directly above 
upon the lamp-rail. This, however, is being done less and less, be- 
cause unless the beam is masked from the wall, the result appears 
artificial. Much more frequently the beam will be projected down- : 
ward from front or side. In this connection, it may be mentioned 


that although the majority of sets are still three-sided, the lamp-rails 
overhead are in an increasing number of instances four-sided. 

Over and above these familiar effects, set-lighting is more and more 
frequently employing the artifice of casting decorative shadow-pat- 
terns upon otherwise flat wall areas. Properly executed, this trick 
enhances the composition, and adds variety to the otherwise monot- 
onous flat effect of the prevalent light-walled sets. 

The technic of "key lighting," while it can not wholly be said to 
have come into use only during the past few years, has certainly 
gained in importance lately. Fundamentally, it refers to the logical 
practice of lighting sets directionally; that is, keying the lighting to 
some logical angle of lighting, usually suggested by the design of the 
set. That does not mean that all the lighting should come from the 
one direction, but that the predominant highlights should appear to 
come from the direction of some source established by the scene. 
For example, imagine a set representing a modernistic penthouse. 
Let us say that on the left of the camera are broad windows through 
which can be seen an expanse of New York's skyline, only slightly oc- 
culted by skyscrapers. In reality, we should expect most of the 
illumination in such a room to come from the obvious source the 
windows. In a key-lighted set, the dominant lighting would appear 
to come from the windows, although actually it would not. A strong 
source-light, probably from some unit like an H. I. arc, would project 
a clear-cut beam similar to sunlight through the windows. The 
primary modelling lighting on both set and actors would come from 
angles suggesting the windows as the source. Beneath this key 
lighting would still be the vitally necessary secondary modelling 
lighting, coming from other angles, giving to the scene depth and 
roundness that would not result if all the light came from the key 

The key lighting does not by any means have to be obvious. It is, 
in fact, best if it fits unnoticeably into the general scheme of lighting. 
But by arranging the lighting to coordinate with a definite key-light, 
the cinematographer is able to create effects affording a superior il- 
lusion of actuality. Noticed or not, the effects are more logical and 
believable. Effect-lighting may be called an exaggerated develop- 
ment of this technic. Generally it refers to extreme and unusual 
lighting, often appearing to come solely from one source, as from a 
fireplace, table lamp, or the like. 

The lighting of close-ups is too intricate a subject to be dealt with 

182 E. C. RICHARDSON [J. S. M. p. E. 

in detail at this time. In the first place, it is an intensely individ- 
ual matter, varying not only with the technic of the individual 
cinematographer, but with the requirements of each player: One 
player, Marlene Dietrich, for example, may appear to best advantage 
under strong key lighting projecting downward upon her face; an- 
other, such as Mae West, may require the softest of diffuse flat light- 
ing ; a third, for example, Irene Dunne, may look best when her face is 
softly illuminated by focusing a "baby" spotlight fitted with a ma- 
genta filter, into her eyes, to enhance their natural sparkle. 

Speaking broadly, much of this personal lighting which was done 
only a few years ago by diffused broadsides or rifles, is now done by the 
more controllable beams of spotlights. The new Junior Solarspot is 
a prime favorite for this service, while the newer 500- watt baby Solar- 
spots are coming into increasing favor. The even distribution of 
their Fresnel-type lenses, together with the greater intensity in com- 
parison with conventional condenser-spotlights, and the wider range 
of usable beam divergences when compared with mirror-type lamps, 
are winning these units an important place in personal lighting. 

In making moving-camera shots, in which the camera follows the 
actor about the set, close-up or medium, it has become very popular to 
mount a suitable lamp directly upon the camera-blimp. The "Handi- 
lamp" or "Lupe" has been very popular, and more recently the more 
precise small Solarspots are being used extensively for such service. 

Individual dimming devices are being used more and more, so that 
any given lamp may be dimmed imperceptibly as a character walks 
into or across its beam, and then restored to normal brightness 

Until the last few months, the foregoing applied chiefly to black- 
and-white cinematography. Due to various limitations, natural- 
color cinematography was felt to require flatter lighting. Within the 
past six or eight months, however, color cinematography has made 
immense strides toward parity with monochrome. Great improve- 
ments have been made both in negative processing and in printing 
methods, which have made it possible to attain better results with 
more normally lighted color scenes. At the same time, newer and 
more efficient arc spotlighting equipment has been made available in 
the H. I. arc and Ultra H. I. arc. 

It is well known that the best results in interior natural-color cine- 
matography are attained by using light^sources that closely approxi- 
mate the spectral distribution of natural daylight. This presupposes 


arc lighting, although earlier arcs, in addition to their unsteadiness, 
often emitted an overly bluish light. The present high-intensity H. I. 
arc spotlights, as used in Technicolor production, have corrected these 
faults. Careful attention to the physical and mechanical aspects of 
the burning of the carbon eliminated the flicker, and improvements 
in the carbon itself helped to reduce the excess of blue and ultraviolet 
radiation. Today, the H. I. arcs burn almost as steadily as incan- 
descent lamps, and require only very light straw-colored gelatin 
niters for correction to daylight standards. Optically their construc- 
tion is similar to that of the Morinc-lensed Solarspots ; like them, they 
afford a photographically satisfactory distribution of light within 
the beam at all divergences from 8 to more than 45 degrees. 

Accordingly they are used identically in the way in which Solarspots 
are used in black-and-white cinematography. A somewhat higher 
level of illumination is still required for color, but it has been consider- 
ably reduced of late, and is coming every day into closer agreement, 
unit for unit, with black-and-white practice. The arrangement of the 
lighting units for color is identical to the arrangement in black-and- 
white practice. The formerly dominant general lighting units- 
side arcs on the floor and scoops overhead have virtually vanished, 
except from unusually large sets. Speaking conservatively, more 
than 95 per cent of the lighting of a Technicolor production is now 
effected by H. I. arc spotlighting equipment. The methods and 
effects are virtually identical to those in the best monochrome pro- 
ductions. In some respects, it may be said that color lighting 
methods and equipment are in advance of those commonly used for 
black-and-white, but for economic reasons, rather than technical. 
For color, it was necessary to obtain new lighting equipment through- 
out; for black-and-white, replacement necessarily has had to be 
slower, because a vast supply of usable though obsolescent equip- 
ment existed. As the advantages of the newer technic, which may 
be called "precision lighting," become more and more apparent, it 
will not be very long until we shall find the old-time concept of set 
lighting as floodlighting extinct, and replaced by precision lighting of 
sets as well as actors with the more precise tools of modern spot- 



Summary. The principles and characteristics of various types of power-level 
indicators used in sound recording are described, including the copper oxide, various 
vacuum-tube devices including the peak-reading meter, and the recording types of 

Continuous measurement of the level variations of speech or music 
handled by sound recording systems is essential to satisfactory opera- 
tion. These measurements assist in the satisfactory delivery of 
program material from its point of origin to the ears of those interested 
in its reception. The device employed is called a volume or power- 
level indicator. The purpose of the indicator is two-fold: it must 
permit controlling the system to which it is connected so that its 
practical operating limits are not exceeded, and it must be capable of 
indicating a range of power-level variation with respect to these 
limits. The character of the distortions that result from overloading 
is too well known to require discussion here. The control of level 
in a sound recording system is perhaps more important than that 
ordinarily required in communication systems due to the use of 
electromechanical devices as modulating units. These in general 
have sharply defined overload points, and the effect of exceeding 
these limits is quite detrimental to sound quality. 

The characteristics that a power-level indicator should possess 
vary with the service for which the device is intended. It is the pur- 
pose of this paper to discuss the various types of power-level indicators 
employed in sound recording and their characteristics. 

While various types of devices are used, there are certain funda- 
mental requirements to be fulfilled if the device is to be completely 
adequate. The requirements may be summarized as follows : 

(a) The power-level indicator should be easily read, and capable of being inter- 
preted so that various observers may obtain substantially similar results. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received May 
20, 1937. 

** Electrical Research Products, Inc., Hollywood", Calif. 


(ft) By the use of the power-level indicator it should be possible to modulate 
fully the recording device without overloading it. 

(c) A long-scale range is preferable, since for low-level passages it is essential 
to make adjustments such that the recorded sounds will be above the noise level. 

(d) It is desirable that the device have the same response characteristic as the 
recording system with which it is used. 

Most power-level indicators consist primarily of a rectifier of some 
type and an indicating meter. The rectifier may be of either the 
copper-oxide or the vacuum-tube type. The more flexible devices 
usually have an adjustable attenuator and one or more stages of ampli- 
fication preceding the rectifier and meter, while the simpler types 
consist of only the copper-oxide rectifier, an indicating meter, and a 
fixed or variable series resistance. 

The meter is usually a d-c. milliammeter, which is operated by the 
current from the rectifier or vacuum tube. In addition, various 
types of meters are employed having various operating speeds and 
amounts of damping. Proponents of the high-speed types of meter 
claim that the rapid variations in the speech or music waves may be 
more easily followed, and that advantage may be taken of this to 
modulate the recording device more fully without detectable over- 
loading. Advocates of the slow-speed meters claim that the rapid 
movements are confusing, and that the slower movement more nearly 
represents the integrated effect that the ear perceives. It should also 
be mentioned that the kind of circuit associated with the meter may 
have a decided influence upon its operating speed. 

Since most d-c. indicating meters have uniform current scales, the 
scale becomes non-uniform when calibrated in decibels, since the deci- 
bel is a logarithmic function. Meters having uniform decibel scales 
may be designed by properly shaping the pole-pieces surrounding the 
moving coil so that the flux density surrounding the conductors in the 
moving coil varies with the position of the coil. 1 Use has been made 
also of the logarithmic relation between grid current and voltage in a 
vacuum tube to produce a logarithmic indication with the usual type 
of meter. A description of some of the various types of power-level 
indicators follows: 

Copper-Oxide Type. A copper-oxide rectifier and a d-c. indicating 
meter together constitute the simplest device widely used for measur- 
ing volume variations. The circuit of such an indicator is shown in 
Fig. 1, and includes a series resistance for adjusting the sensitivity. 
The circuit under measurement is connected through the resistor to 



[J. S. M. P. E. 

the full-wave copper-oxide rectifier, which in turn supplies current to 
the indicating meter. Such devices usually have relatively high 
impedances and may be bridged across 500-ohm circuits without in- 
troducing excessive loss. They 
indicate the average value of 
the wave to be measured, hence 
the meter deflection is propor- 
tional to the input voltage. 
The response characteristic is 
usually uniform over the audio- 
frequency range. 
FIG. 1. Copper-oxide indicator. A more flexible type of vol- 

ume indicator is shown in 

Fig. 2. Here the copper-oxide rectifier and indicating meter are 
preceded by a single-stage vacuum-tube amplifier provided with a 
gain control. 

A variety of indicating meters having movements of different 
speeds are available. The high-speed types have excellent damping 
characteristics, so that there is very little overswinging of the meter 
needle. Where minimum space and equipment are essentials, these 
instruments have found wide fields of use. 

Thermocouple Type. One of the earlier types of instrument em- 
ployed a thermocouple in conjunction with a d-c. indicating meter. 
The readings were a function of the PR losses occurring in the heater 
element, and the action was slow due to the thermal inertia of the ele- 
ments employed. The indications were proportional to the power 
in the input wave integrated over an appreciable time. 

FIG. 2. Copper-oxide indicator with amplifier and gain 

Vacuum-Tube Types. A vacuum-tube power-level indicator is 
shown in Fig. 3. The plate current from a .grid-biased vacuum-tube 
detector operates a d-c. meter in the plate circuit. Since this type 

Aug., 1937] 



was widely used in communication work -when motion picture sound 
recording began, it was generally adopted and has been used in sound 
recording essentially without modification until recently. 

The integrating grid-blocking type was one of the early devices 
employing a vacuum tube. In this instrument the floating grid of a 
vacuum tube was biased by the charge accumulated in a condenser 
coupled to the circuit being measured. After a given length of time 
the plate current of the tube was measured, and the voltage existing 
on the grid determined from a previous calibration. The condenser 
was then discharged and the device again connected to the circuit 
under measurement. Such a device gives an integrated reading of 
the voltage variations occurring in the measuring circuit over the 
period of time during which it was connected. Since it does not 

FIG. 3. Simple vacuum-tube indicator. 

give a continuously varying reading, it has no practical application 
to sound recording. 

Peak-Reading Power-Level Indicator. Peak-reading power-level in- 
dicators give indications that are a function of the peak value of the 
input wave 2 ' 3 - 4 ' 9 and are essentially independent of form-factor. They 
are adaptable to sound recording because such systems usually have 
a sharply defined overload point, due to the electromechanical devices 
used as modulating units. The overload point is therefore effec 
tively determined by the peak value of the applied wave, rather 
than by either the rms. or average value. The circuit of such a 
power level indicator is shown in Fig. 4, and its operation is as follows : 

The voltage to be measured is applied to the input, passing through 
a network having the response characteristic of the system whose 
volume variations are being measured. If the system is uniform in 



[J. S. M. P. E. 

response, the equalizer may be omitted. A sensitivity control (s) 
precedes a stage of amplification (A). The amplified voltage is then 
applied to a full- wave rectifier (R), the rectified voltage in turn charg- 
ing a capacity (C) shunted by a resistance (r). The grid of a triode 


FIG. 4. Peak -reading power-level indicator. 

(T) is biased by the rectified voltage and controls the flow of plate 
current through the indicating meter (M). 

The speed of operation of the device is determined by the value of 
the capacity (C) and the impedance of the rectifier. The restoring 
time is a function of the capacity and the resistance that shunts it. 
By properly choosing the circuit elements, fast operation with rela- 
tively slower restoration may be attained. Such a condition is de- 

40 80 120 160 





FIG. 5. Operating speeds of typical power -level indi- 
cators. (1) peak indicator; (2) high-speed copper- 
oxide; (5) usual vacuum-tube indicator. 

sirable because it permits more accurately determining the point to 
which the meter needle is deflected. 

A long-scale meter having suitable damping characteristics may be 
used with such a circuit. Since the current through the meter is 


maximum when there is no input voltage, the simple expedient of 
mounting the meter upside down, or of reversing the meter move- 
ment, permits reading the indications from left to right, as with ordi- 
nary meters. Since the greater the applied voltage, the lower will be the 
current flowing through the meter, it is impossible for excessive inputs 
to damage the meter, as with most other systems. The meter is placed 
in the cathode circuit and hence is practically at ground potential. 

The operating speeds of several typical power-level indicators are 
shown in Fig. 5. Impulses of varying duration were applied to the 
inputs of the indicators. For a steady sine-wave input the meters 
gave readings that, for convenience, were chosen as reference points. 
For impulses of the same amplitude but decreasing duration, the de- 
flections of the meter become proportionately less, approaching zero 
as the impulse time approaches zero. The curve shows the impulse 
time in milliseconds plotted as abscissa, and the meter deflection in 
db. below the reference point as ordinates. The peak meter more 
nearly approaches the steady-state reading for short impulses than do 
the other types illustrated. The measurements were made in the 
following manner : A tone- wheel was used to interrupt a light-beam 
which in turn modulated a photocell. The resulting photocell current 
was amplified and used as the source of tone for operating the volume 
indicators. A calibrated variable-speed shutter interposed in the 
light-beam made it possible to apply impulses of varying duration to 
the power-level indicators under test. 

Tests with this type of indicator showed that if the power-level 
indicator had a fast operating and fast restoring time, peaks were 
consistently read 2 or 3 db. lower than if the restoring time were rela- 
tively long compared with the operating time. The slower restoring 
time permits more accurate observation of the point to which the 
needle is deflected. 

Recording Power-Level Indicators. For certain kinds of studio work a 
continuous graphical record of volume variations may be desirable. 
To obtain such a record, a d-c. operated recording chart meter may 
be connected to the output of nearly any of the previously described 
vacuum-tube power-level indicators. If a logarithmic deflection of 
the chart meter pen is required, it may be obtained by appropriately 
designing the meter or modifying the circuits supplying the meter. 

Such a recording indicator may be used for routine studio trans- 
mission tests, affording printed records that are quickly made and 
filed for future record or reference. For certain special services, 

190 F. L. HOPPER 

such as re-recording, it has been suggested that some such printed 
records of volume variations might be of value in determining the re- 
corded volume range and number of overloads occurring in the re- 

Many other automatic curve-drawing instruments have been de- 
scribed in the literature. 8 ' 6 ' 7 ' 8 In general, they are more elabo- 
rate, employing motor-driven attenuators (to which a pen is at- 
tached) that balance the variable input voltage to the device against 
the output of its amplifier system. 


1 BEST, F. H.: "Decibel Meters," Bell Lab. Record, XV (Jan., 1937), No. 5, 
p. 167. 

2 THILO, H. G., AND BIDLINGMAIER, M.: "Die Tonmesser, ein sparrnungs 
spitzenmesser mit logarithmischer anzeige," ENT, XIII (1936), No. 5. 

3 JOLLIFFE, C. B.: "The Use of the Electron-Tube Peak Voltmeter for the 
Measurement of Modulation," Proc. I. R. E., XVII (April, 1929), No. 4, p. 660. 

4 "Thermionic Peak Voltmeter for Use at Very High Frequencies," /. /. R. E. 
(London), 77 (Sept., 1935), No. 465, p. 429. 

5 BEST, F. H.: "A Recording Transmission-Measuring System for Telephone 
Circuit Testing," Bell Syst. Tech. J., XII (Jan., 1933), No. 1, p. 22. 

6 BALLANTINE, S. : "Logarithmic Recorder for Frequency Response Measure- 
ments at Audio Frequencies," /. Acoust. Soc. Amer., V (July, 1933), No. 1, p. 10. 

7 SLONCZEWSKI, T.: "Automatic Measurement of Transmission," Bell Lab. 
Record, XV (Oct., 1936), No. 2, p. 56. 

8 PEACHEY, F. A.: "Automatic Line Level Recording Apparatus," Wireless 
Engineer (Sept., 1936), No. 9, p. 462. 

9 READ, S., JR.: "A Neon Type Volume Indicator," /. Soc. Mot. Pict. Eng., 
XXVIH (June, 1937), No. 6, p. 633. 


MR. TASKER: There was no discussion of the neon volume indicator. 

MR. HOPPER: That is true, Mr. Tasker. The reason for not discussing it was 
the lack of published information relating to the subject. A paper was presented 
at the Fall Convention describing such a device, but it has not yet been pub- 
lished. Devices of this general type are capable of measuring wide volume ranges, 
but are usually somewhat complicated electrically, and are difficult to read in the 
presence of light. 

Incidentally, we have made listening tests using a copper-oxide volume in- 
dicator of high speed and a peak volume indicator. The peak meter was ad- 
justed to have a slower restoring than operating time. Using these two types 
of devices and listening to various sorts of dialog and music, picked up through a 
recording channel and reproduced over a loud speaker from the photoelectric cell 
monitor, the peak meter indicated very close correlation between overload as 
read on the meter and that heard in PEC monitor ; while for the high-speed cop- 
per-oxide type such close correlation did not exist. 


Summary. In the past year and a half light-weight microphones and new 
pick-up equipment have been made available. The apparatus described in the paper 
consists of a fish-pole type of microphone boom with accessories, and a complete stage 
pick-up unit. The boom is readily adaptable to a number of pick-up conditions 
where light weight, small size, and ease of handling are necessary. 

The stage pick-up unit is readily portable and of relatively small weight and size. 
It includes the pick-up amplifier, booster amplifier, and power supply, with a small 
amount of storage space. It completely replaces the large type of monitoring booth 
previously employed. The weight of the unit being about 300 pounds, a great saving 
in operating cost is effected and greater simplicity of operation achieved. 

Within the past two years Electrical Research Products, Inc., 
have made available to the industry certain equipment that can be 
so combined as to provide complete small-sized recording units with- 
out sacrificing fidelity. The items that primarily made this possible 
were a new head-set having far greater frequency range than previously 
obtained, the 630-A transmitter, and the type Q recording equipment. 
Simultaneously, Paramount decided to modernize its recording equip- 
ment. After tests of the new head-set had been made it was agreed 
that the large-size monitoring horn and booth then being used could 
be dispensed with, and the equipment combined into some sort of 
dolly or cart. 

The type Q recording equipment decided upon consists essentially 
of three items: the pick-up amplifier, the main amplifier, and the 
power supply providing complete a-c. operation. The requirements 
for the dolly or cart were as follows : 

(1) The weight of the complete unit should be no greater than two men 
could handle on a set, or move from storage to stage. 

(2) The size should be such as to allow working between lights, near the 
action, through doors, etc. 

(3) A small amount of storage space should be provided for scripts, circuit 
drawings, microphones, and head-sets. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. 
** Paramount Pictures, Inc., Hollywood, Calif. 




[J. S. M. P. E. 

FIG. 1. Front view (open). 

(4) The unit should be comfortable to operate. 

(5) Pneumatic tires should be used, to reduce shocking the equipment during 

(6) It should be durable and maintain its finish. 

(7) It should have a good appearance. 

FIG. 2. Rear view (open). 

Aug., 1937] 



Requirement 6 practically demanded metallic construction or 
sheathing, and to conform to requirement 1 the choice must of neces- 
sity be aluminum or duralumin. Duralumin was chosen. Small 
pneumatic tires and wheels, intended for toy automobiles, were se- 
lected to fit requirement 5. Requirement 4 indicated that the desk 
should be of normal desk height. For the finish we decided to sand- 
blast the duralumin and then apply a coat of clear lacquer, thereby 
completing requirement 6 and fulfilling 7. 

Having made preliminary drawings, the first model 
was built by applying sheet duralumin over a plywood 
frame, but the construction was somewhat laborious, 
was not sufficiently rigid, and did not give the appear- 
ance of a finished job. It was found that to eliminate 
the wood frame and use duralumin completely would 
add only very few pounds to the weight. The first 
model, however, proved that a practicable size had 
been achieved without undue weight and that the 
fundamental idea of the design was correct. From this 
the final units were designed. 

Fig. 1 shows the front view of the unit with the 
lid open. The drawer for scripts, reports, and draw- 
ings is seen on the left. The chassis is made of Shelby 
tubing pinned and welded together and then chromium 
plated, all of which lends a somewhat modern appear- 
ance. The bars on the sides are used to hold spare 
microphone cable ends and to provide handles. The 
castors were specially made so as to harmonize with 
the design and enhance the appearance. The body 
contains no wood except in the equipment panel and 
desk, the assembly being made by welding and riveting 
the 17 ST 14-gauge duralumin. The wood on the desk- 
top is provided primarily to eliminate the coldness of the metal and 
for easy replacement when the top becomes scarred from usage. The 
body is held in place by four straps passing over the tubular chassis 
and fastening to the ends of the body. For the sandblasting it is de- 
sirable to use a very fine sharp sand at low air-pressure, otherwise 
warping of the metal panels will occur. 

The storage compartment in the upper left was provided for hand- 
sets, head-sets, and microphones. The panel on the right carries the 
main a-c. supply switch and stage warning lights, and has some space 

FIG. 3. 
type of hand 

194 L. D. GRIGNON [J. S. M. P. E. 

to spare for future devices. The pick-up unit is a standard RA 1001 
amplifier, and a trap-door is provided in the knee space for access 
to the vacuum tubes of this amplifier. 

Fig. 2 shows the rear opened. The receptacles for the microphone 
connections can be seen through the door of the upper compartment, 
in which a lamp has been provided for illumination. In the lower 
right compartment is located the RA 1002-A main amplifier, and in 
the left the RA 1005 power supply for both amplifiers. The plugging 
panel for stage cable is at the center. Metering the RA 1002-A 
amplifier and the power supply is accomplished through doors in the 

The whole unit, designated in the studio as a "stage pick-up unit," 

has a weight of 355 pounds, 

J^AL ^f^^ of which 185 pounds is 

'v^k -^r ^^ equipment alone. The unit 

^f^ ^ measures 56 inches long, 38 

g^E| high, and 25 wide. 

PvKl^^ As now used, this com- 

^Pr^^ii^. ^^^ plete unit replaces a stage 

^^^B ^^^ monitoring booth weighing 

Bk about 2000 pounds and 

containing wet and dry 

B batteries, mixing panel, two 

iJP^^ amplifiers, and monitoring 

e , , t .. t - A and talk -back horns. The 

FIG. 4. Shock-proof mounting for 630-A 

transmitter. pick-up unit also replaces 

booster amplifiers previ- 
ously installed in the recording building. In other words, it con- 
tains a complete sound recording channel except for the recorder and 
associated equipment, and the motor system. 


The 630-A transmitter was mentioned earlier as a contribution 
to lighter stage equipment, which is obvious when considering its 
small size and its weight of only 14 ounces compared to the obsolete 
394 condenser transmitter and 47 or 53 amplifier having a weight of 
about 18 pounds. On certain kinds of shots the stage men found that 
by placing the microphone at the end of a pole better pick-up results 
could be achieved than could be attained with the large microphone 
booms, and with a great saving in set-up time. As a consequence, 

Aug., 1937] 



having received many demands for bamboo poles for this purpose, 
we built a number of duralumin poles that telescoped from 8 to 15 
feet. Fig. 3 shows the pole, commonly termed a "fishpole." The 
assembly at the end, for supporting the 630- A transmitter, is insulated 
from the pole by Lord rubber mountings, as shown in Fig. 4, and the 
cable is supported internally by sponge rubber rings to prevent its 
banging or sliding about and causing noise as the pole is handled. 
As it becomes quite an impossible job to hold this pole continuously 

FIG. 5. Light roller standard for "fishpole" boom. 

during a long scene, two bases were constructed so that the pole 
could be used on the base or removed and held in the hands. 

In Fig. 5 is shown a standard mounted upon a common 18-inch 
lamp-stand and equipped with a roller at the top. The roller is made 
of leather disks bound together by two duralumin disks. The stand- 
ard is free to rotate on its axis. The unit is operated by one man who 
grasps the rear end of the pole and moves it about, up or down, in 
or out, as the action requires. 



Another base, still in the experimental stage, is shown in Fig. 6. 
In-and-out motion is accomplished by moving the front upright sec- 
tion of the parallelogram, and the up-and-down motion is achieved 
by the handle at the rear. The weights provide a degree of counter- 
balancing. The stand is again the commonly used 18-inch lamp- 
stand. The in-and-out motion of the microphone is made approxi- 
mately straight-line by making the rear upright of the parallelogram 
somewhat shorter than the front. A total usable movement of 5 

FIG. 6. Light-weight parallelogram boom. 

feet is realized with this unit. Credit for the idea of using an un- 
balanced parallelogram for this purpose is gratefully given to Uni- 
versal Studios. Possible improvements of this preliminary design 
are no doubt obvious. 

Use of this equipment results in considerable saving, because less 
labor is required to move equipment. The production company 
can move from one set or location to another in less time, and opera- 
tion is improved because the operators are less hampered by equip- 
ment limitations. 



Summary. The Engineering Department at the Twentieth Century- Fox Film 
Studios is responsible for the various technical operations of the studio, which can be 
classified under the headings of Air-Conditioning, Plumbing, Foundry, Mechanical, 
or Electrical activities. These responsibilities cover a considerable portion of the 
technical activities of a studio, and a great deal of effort is required to take care of the 
routine matters that arise each day. However, the interesting work of this department 
lies in the special engineering problems that arise in the production of motion pictures. 
The paper describes some of the various engineering problems that have been en- 
countered in the production of motion pictures at this studio. 

The Engineering Department at the Twentieth Century-Fox Film 
Corporation Studios is responsible for the various technical operations 
of the studio, which can be classified under the headings of air-condi- 
tioning plumbing, foundry, mechanical, and electrical activities. 
These responsibilities cover a considerable portion of the technical 
activities of the studio, and a great deal of effort is required to supply 
the studio with these services efficiently and smoothly. 

One of the most important departments is the electrical, which is 
divided into two groups. One is the operating group, which follows 
each picture production closely and supplies all the requirements for 
lighting the sets. The other is the maintenance and construction 
group, which is responsible for all permanent equipment. 

The head of the operating group attends the daily production meet- 
ings and finds what the requirements of each company are for the fol- 
lowing day. He sees that the sets to be used are rigged and supplied 
with all the necessary equipment so that the shooting crew can walk 
upon the set the next morning and go to work immediately. The 
equipment must be removed from the sets promptly after the sequences 
have been photographed and approved, and installed on working sets 
with the greatest dispatch. One of his most important duties is to 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
May 20, 1937. 

** Twentieth Century-Fox Film Corp., Hollywood, Calif. 


198 W. T. STROHM [J. S. M. p. E. 

schedule the equipment properly and keep it moving quickly from set 
to set, as thousands of dollars in rentals can be easily incurred due to 
allowing the lighting equipment to stand on sets that are dressed but 
not working. 

The chief electrician in charge of lighting on each set is called the 
"gaffer." He and his assistant, the "best boy," must be able to meet 
all requests of the cameramen on the set. They must have available 
Sun arc lamps for shadow or sunlight effects, and diffusion disks of 
every conceivable material to produce the degree of diffused light re- 
quired on the face of the star. Each cameraman and each production 
(color or black-and-white) requires a different assortment of lamps, 
both incandescent and arc. Lamps with plain reflectors, special cor- 
rugated or parabolic reflectors, spotlights with various lenses, lamps 
with different degrees of adjustable diffusion or concentration, dim- 
mers, lamps of various color characteristics, special effects to create 
lightning, wind machines, portable generators, and a thousand and one 
special items are in constant use. All this equipment must operate 
silently so that it does not record, which is also a difficult problem at 

The maintenance and construction group install, operate, and main- 
tain all permanent equipment. They operate and maintain the tele- 
phone system which consists of a private branch-exchange with twelve 
operators. They keep the lamp equipment in proper working condi- 
tion, operate the power house, and maintain the lighting and power 
system in the studio, and more than 700 motors having a total output 
of 9000 hp. in this studio. The general lighting and heating load is 
2400 hp., the total load being more that 11,000, which is equivalent to 
that required by a city of 20,000 inhabitants. 

The duties of the ventilating, plumbing, and air-conditioning groups 
are obvious. All the stages, projection rooms, and executive offices 
are completely air-conditioned. Due to the enormous volume of the 
sound stages a large amount of equipment is required but the increased 
efficiency of the production units has more than justified the cost. 

The plumbing department maintains the water supply system, the 
automatic fire sprinkler system, and a high-pressure gas system, 
and also installs all the plumbing fixtures on the sets. One problem 
that is troublesome at times is to supply the sets with artificial rain. 
The rain must not fall in "chunks" in front of the camera, but must 
consist of raindrops of normal size falling with required intensity. 

The motion picture industry requires many devices for creating 


special effects for use by the various production units, most of which 
are impossible to obtain commercially. In addition to these devices, 
which must be built in the studio, there is always required a large 
amount of mechanical work on the various sets, as well as having to 
construct equipment such as camera booms, camera cranes, gas- 
driven generators, special wind machines, lighting equipment of all 
kinds, and special-effects equipment. For that reason the department 
operates a design group, which prepares the plans; a foundry, which 
supplies the castings; and a very completely equipped machine shop, 
which fabricates all the various devices. 

In addition to the normal routine work of the various groups, 
special problems handled by the engineering department cover every 
conceivable request that can be made by a dozen production units, 
each busily engaged in making a motion picture. As an example, one 
of the most interesting problems that required solution was the con- 
struction of the ice-skating rink used in the recent Sonja Henie pic- 
ture, One in a Million. This task was a little unusual, and it is believed 
that this ice-skating rink was the first of its size and kind to be used on 
a motion picture stage. 

Heretofore, most ice-skating sequences in motion pictures have been 
accomplished with artificial ice consisting of hypo, specially applied. 
This artifice was at first suggested, but was instantly ruled out due to 
the fact that the featured player is the woman champion figure 
skater of the world, and artificial ice would not have been adequate to 
serve the purposes called for in the picture. 

The production executives asked the engineering department to 
construct immediately a natural ice-skating surface to cover an area of 
80 by 130 feet. The problem that the department had to overcome 
was to construct and install the rink in fourteen days. It was believed 
by the various contractors who estimated the job to be an impossible 
task but the rink was completed within the required time, and Miss 
Henie was skating on the rink and had approved it within that period. 

A great number of problems presented themselves during the 
course of the work. It would be impossible to list them all but a few 
of the more important ones will be mentioned : 

It was not sufficient to enclose the skating rink in a large stage and re- 
duce the temperature of the entire stage below the f reezingpoint, because 
the temperature on the set had to be kept high enough so that the 
breath condensation of the players would not show up in intimate 
close-up scenes. Due to the great difference in temperature between 

200 W. T. STROHM [J. S. M. P. E. 

that of the ice and that of the atmosphere on the set, a fog was created 
that rose from the ice and obscured the figure skating of the star, 
especially her feet. The situation was further complicated by the 
tremendous amount of heat liberated by the large number of Incandes- 
cent lamps necessary for photographing the set, which so increased the 
temperature of the air as to make the freezing process a difficult task 
and to cause more fog to rise from the ice. 

Special provisions had to be made to keep the ice uniform and free 
from irregularities at all times. Great precautions had to be taken to 
keep the ice clear of small particles, which are bound to drop at times 
from the catwalks and parallels on which the lighting equipment is 
mounted above the set and on which a large number of men neces- 
sarily work. If a particle no larger than a pin dropped upon the ice 
it would soon adhere to the frozen surface, and at the speed with which 
Miss Henie skates would present a danger to be considered and dealt 
with promptly. 

Another problem was that of providing heating arrangements for 
the comfort of the actors on the set when they were not in front of the 
cameras. This was solved by constructing specially designed dressing 
rooms right on the stage itself. 

As soon as the rink was constructed and operating properly, the 
photographic department found that for a certain sequence there was 
not sufficient contrast between the ice and the action to be photo- 
graphed. "White ice" was requested for this sequence to improve 
the photography. The request caused much head-scratching, but 
was solved by painting the surface of the ice with white paint, after 
which another quarter-inch of the clear ice was frozen over the paint, 
resulting photographically in "white ice." 

Another very interesting problem arose during the production of 
Banjo on My Knee. The engineering department was called upon to 
produce a river capable of handling house-boats such as were common 
on the Mississippi River and to produce a storm on the river that 
would wreck a house-boat of such size. A large moat was dug and 
filled with water. Pumps capable of delivering 20,000 gallons of 
water a minute converted the moat into a swiftly flowing and turbu- 
lent river. For the storm that finally sent the house-boats to their 
destruction, great wind machines were used, and six large spill buckets, 
each containing 2500 gallons of water, were dumped into the stream 
against the already swaying and pitching house-boats. Accompanied 


by flashes of lightning and peals of thunder the effect produced in the 
finished picture was very satisfactory. 

Problems of coordinating and timing the various special effects in a 
picture often call for a great deal of ingenuity. An example of tuning 
mechanical equipment occurred in the recent production On the 
Avenue. A series of sets, each mounted on a movable train, had to 
move across the stage in front of the camera exactly in time with the 
recorded music. An electric truck was used to pull the train, and to 
synchronize the speed of the truck with the music proved quite a prob- 
lem. It was finally solved by ingeniously altering an electric welding 
generator to supply the power to the truck, and an efficient and flex- 
ible speed control was provided that could be exactly synchronized 
with the music. 

Each picture presents distinct and different problems that must be 
solved before production is started. The foregoing examples give 
some idea of the great diversity of the problems that are encountered 
in a studio in addition to the regular routine work of the department. 


During the Conventions of the Society, symposiums on new motion picture appara- 
tus are held, in which various manufacturers of equipment describe and demonstrate 
their new products and developments. Some of this equipment is described in the 
following pages; the remainder will be published in subsequent issues of the Journal. 



A recording machine for use in present-day commercial production of sound- 
film must not only be capable of propelling film at a constant velocity to produce 
high-quality records but must also be designed for simple, rapid, and flexible 

The Western Electric recording machine described in this paper was designed 
to fulfill these requirements after an extensive investigation of approved studio 
practices and of mechanical, electrical, and optical means best suited for sound- 
film recording. It is ruggedly constructed of materials selected to give long life 
with a minimum of maintenance, and all operating mechanisms are enclosed in a 
compact housing of pleasing appearance. 

Fig. 1 is a front view of the recorder with doors closed and film magazine in 
place. Fig. 2 is a closed rear view, showing the housing on top, which contains a 
film take-up and drag mechanism, and, at the bottom, four connectors into which 
may be inserted plugs attached to cabling for all outside circuit connections. 
The handwheel shown at the left end may be used for turning the film-driving 
mechanism of the machine. 

Film-Driving Mechanism. The fundamental requirement of a film-recording 
machine is to propel film past the recording light-beam at a constant speed. In 
this recorder constancy of film speed is attained by a positive sprocket drive sys- 
tem similar in principle to that employed in the Western Electric recording ma- 
chine, which has been in use in studios since 1927, but incorporating a number of 
improvements to assure even more constant and reliable film speed and, conse- 
quently, sound records with greater freedom from flutter effects. 

The film drive system may be seen in Fig. 3, which is a view of the film com- 
partment of the recorder. The film is propelled through the machine by means 
of two sprockets driven by a constant-speed motor and a worm reduction-gear 

* Posthumous; presented at the Spring, 1937, Meeting at Hollywood, Calif.; 
received May 24, 1937. 

** Bell Telephone Laboratories, New York, N. Y. 






FIG. 3. Film compartment. 

FIG. 4. Rear view, opened. 


system. The smaller pull-down sprocket located in the upper left-hand corner 
of the compartment is directly connected to the gear system. It pulls the film 
from the magazine and also holds back the film, as it leaves the recorder, against 
the pull of the film take-up mechanism, thus isolating that section of the film 
upon which sound is being recorded from disturbances in the magazine mecha- 

The larger of the two sprockets located in the lower right-hand corner of the 
film compartment is the sound sprocket, which propels the film past the recording 
light-beam at the required constant speed. This sound sprocket has been de- 
signed to be used with film having a shrinkage of as much as 0.1 per cent (which 
is greater than found in film used for present-day sound recording) without intro- 
ducing sprocket-tooth modulation in the sound-track sufficient to be noticeable 
in high-quality records of either music or speech. The sprocket is driven by the 
worm gearing through a mechanical filter which prevents slight irregularities pres- 
ent in even the most accurately made gears from affecting the constancy of speed 
of the sprocket. This mechanical filter, shown in Fig. 4, consists of an accurately 
balanced flywheel rigidly mounted upon the sound sprocket shaft, and a viscous 
damped resilient coupling connecting the flywheel to its drive gear. The damping 
element consists of two sylphon bellows connected through a restricted orifice 
and completely filled with a viscous fluid. Any variation in speed of the gear 
system lengthens one of the bellows and shortens the other, thus forcing the vis- 
cous fluid through the orifice and producing a damping action that effectively 
prevents the flywheel from oscillating. The viscosity of the damping fluid does 
not change sufficiently over the temperature range of +20 to 4-130 F. to 
affect appreciably the damping action of the mechanical filter. 

By properly proportioning the mass of the flywheel, elasticity of coupling 
springs, size of orifice, and viscosity of damping fluid, the mechanical filter effec- 
tively restricts variations in the speed of the sound sprocket to an imperceptible 
amount, especially in the low-frequency range, where speed variations would 
produce a "wow-wow" effect in sound records. It also rapidly stabilizes the speed 
of the sound sprocket after the recorder is started, so that the recording of sound 
may begin in less than two seconds after the motor has come up to its full speed. 

The drive gear system is enclosed in a housing containing a reservoir of oil, oil 
from which is circulated by means of a pump through tubing to the mesh of the 
worm and worm gears and to the sound sprocket gear bearings, which are thereby 
kept constantly flooded with oil while the machine is in operation. Effective 
means have been employed to prevent leakage of oil from the housing, especially 
into the film compartment. The level of oil in the reservoir may be checked 
conveniently on a gauge-glass located in the film compartment. 

Referring again to Fig. 3, it will be seen that threading the film through the 
recorder is simple and rapid. After leaving the storage compartment of the maga- 
zine, the film passes through a guide which holds it in focus for a slating device 
(to be described later), over a roller to the pull-down sprocket, and thence over a 
series of three rollers to the sound sprocket. The middle one of the three rollers is 
mounted in a pivoted frame which is weighted to produce a definite and constant 
tension in the section of the film passing between the two sprockets. This film- 
tensionujg roller assists in keeping the film speed constant at the sound recording 
point by maintaining a constant film load on the filtered sound sprocket. The 


roller of this series nearest the sound sprocket is equipped with spring-retained 
flanges to guide the film past the recording light-beam so that the sound-track 
is located within 0.001 inch of its correct position upon the film. 

After leaving the sound sprocket, the film passes as a loose loop over guide roll- 
ers and through a punch (to be described later), and thence over a guide roller to 
the pull-down sprocket, which maintains the loop against the pull of the film 
take-up mechanism. In going from this sprocket into the magazine, the film 
passes a switch mechanism which is tripped when a loop forms in this section due 
to any failure of the film to take up in the magazine. The tripping of this switch, 
due to the piling up of film, closes a contact that lights a signal lamp on the in- 
strument panel and also operates a relay to stop the motor. By this means the 
is film is stopped before it can pile up in the machine and cause damage. 

All film-guiding and controlling rollers are ruggedly mounted and rotate on 
precision ball bearings having exceptionally low and uniform friction. They are 
lubricated for ordinary life and sealed against leakage of lubricant and entrance 
of dirt. The worm-gear and sprocket shafts of the film-driving mechanism are 
also mounted upon the same type of ball bearings. 

A brake is provided which may be operated from a lever on the instrument 
panel to stop the recorder quickly after current to the motor has been cut off, and 
thereby reduce film wastage. The brake may also be arranged to be operated by 
an electromagnet for remote control. 

The film take-up mechanism contained in the housing on top of the machine in 
back of the magazine consists of a frictional slip clutch driven by a silent chain and 
sprocket gearing from the main drive gears, and is arranged to be coupled to the 
spool in the magazine upon which the film is wound. This slip clutch may be 
adjusted while the machine is in operation. An adjustable slip friction drag 
mechanism also is included in this housing which couples with the pay-off spool 
in the magazine to prevent the film from unwinding too rapidly and to keep it 
slightly taut as it enters the recorder. Either the Mitchell or the Bell & Howell 
film magazine may be used with this recorder. 

A film footage counter mounted on the right-hand door is so arranged that 
when the door is closed it is coupled through gearing to the pull-down sprocket 

Fig. 5 is a front view with the doors opened exposing the film sprockets and 
guide rollers, film punch mechanism, and shutter, in the film compartment at the 
right; and in the compartment at the left, the recording optical system, light- 
valve, monitoring system, slater, and drive motor. All manual controls for oper- 
ating the recorder are accessibly arranged on an inclined instrument panel located 
at the bottom of the housing. 

Modulator and Monitoring System. Light-valves and their associated optical 
systems to modulate the recording light in either the standard or push-pull 
method of recording may be interchangeably mounted upon an optical bench 
located in the left-hand compartment of the recorder. This optical bench is 
equipped with adjusting screws to locate the recording lamp and to focus the 
recording light-beam upon the film. 

Associated with the modulator is an optical system, photoelectric cell, and 
amplifier which provide for high-quality photoelectric cell monitoring of either 
standard or push-pull recording. In the optical system a thin glass plate, located 


in the recording light-beam, between the light-valve and the recording objective 
lens, diverts about 10 per cent of the total useful recording light-beam projected 
into the photoelectric cell, by means of lenses and a prism. The output of the 
amplifier associated with the photoelectric cell is wired to a jack on the instru- 
ment panel for connection to a monitoring head-set receiver. 

The light-diverting glass in the monitoring optical system is readily removable 
for cleaning. It may be replaced by a silvered mirror, so that all the recording 
light-beam may be reflected into the photoelectric cell for testing purposes. A 
jack located in the top of the amplifier and connected into the photoelectric cell 
circuit provides means for connecting a microammeter inte the circuit for the 
purpose of setting lamp current and the noise-reduction biasing current, checking 

FIG. 5. Front view. 

light-valve overload, or, in the case of previous lamp calibration, for checking 
the light- valve spacing. 

Accessories. Several accessory devices that may be mounted as component 
parts of the recorder are provided to facilitate such practices as marking the 
"take" number of the record, punching an identification notch or hole into the 
film and rapidly cutting in or out the recording light-beam. An automatic 
switch for controlling the various operations in their proper sequence is also 

The slater shown in the upper part of Fig. 5 is used to mark photographically 
the "take" number of the film. It contains two counters: one located so that its 
figures are visible through an opening in the left-hand door, when closed, and the 
other located with its figures in the plane of the sound-track center-line. Upon 
operating a push-button on the instrument panel, two lamps illuminate the 


figures on the dials of the latter counter, which are projected upon the sound- 
track ar.ea of the film with a reduction of approximately 4 to 1. A lever on the 
door steps the dials of both counters, which are geared together to operate in 
synchronism so that the number appearing upon the door counter is the number 
photographed upon the film. Additional identification marks may be photo- 
graphed upon the film by inserting cards in slides adjacent to the illuminated 
counter dials. 

An electromagnetically operated punch unit located in the lower right-hand 
corner of the film compartment shown in Fig. 5 may be used to punch a notch in 
the edge or a hole in -the center of the film, as desired. A button on the control 
panel is provided for operating the punch. 

The projection of the modulated light-beam from the light-valve to the film is 
controlled by means of an electromagnetically operated shutter located on the 
wall between the film and optical compartments, as shown in Fig. 5. A switch 
on the instrument panel is provided to operate the shutter, which opens or closes 
in Vaoo second or less. At this speed a definite and sharp line is produced upon 
the sound-track at the cut-off point, which may be used as a synchronizing mark. 
The recording objective lens mounted on the shutter frame is adjustable by means 
of a screw to locate the modulated light-beam at the proper distance from the per- 
forations in the film. 

A switch mechanism contained in the upper housing of the recorder is operated 
from the main drive system to control various operations of the machine auto- 
matically in proper sequence. When the recorder starts, the switch automatically 
changes the current to the recording lamp from its "hold" to its "on" value so 
that it is lighted to full brilliancy before recording begins; it opens the shutter to 
permit the recording light-beam to be projected upon the film after the slater 
marks in the sound-track area have passed beyond the recording point, thereby 
preventing fogging the marks by the recording light, and it disconnects the battery 
from the slater and punch so that these devices can not be accidentally operated 
and damage the film while the recorder is running. Upon stopping the recorder, 
the switch automatically restores the recording lamp current to the "hold" value, 
closes the shutter, and restores the battery to the slater and punch. 

Provisions are made to connect remote-control devices for operating the slater, 
punch, shutter, noise-reduction circuit, etc. 

This sound recording machine has been developed by the Bell Telephone Labo- 
ratories to meet not only the studios' basic requirements, but to facilitate their 
specialized methods. Thus has been provided a recorder that contains not only 
the mechanical elements necessary to film propulsion and sound quality of the 
highest precision, but also those conveniences demanded by the production 
methods of the studios and their operating personnel. 


Mechanical irregularities producing speed variations in recording and repro- 
ducing machinery constitute a source of distortion of sound quality difficult to 
diagnose and eliminate in the usual manner. Electrical measurements of such 
distortion, and especially analysis of the variation rates present, have been found 
to be an invaluable guide in attacking flutter problems. Such measurements have 
been employed in various fields of recording and reproducing and certain instru- 
ments used therein have been described in the literature. 1 - 2> 3 

The instrument to be described here was developed primarily for measurements 
in the laboratory of either frequency modulation (flutter) or amplitude modulation, 
and no efforts have been spared to make it as complete and thorough in its func- 
tions as could be desired. While the principle of operation is basically similar to 
that of a portable flutter-measuring instrument described previously, 2 it differs 
in the provision of more extensive facilities for analyzing the variation rates 

General Description. With the new instrument, frequency variations as low as 
0.01 of 1 per cent of a 3000-cycle signal may be detected and the rates between 
the limits of and 200 per second may be determined. Amplitude modulation 
may also be measured with a maximum sensitivity of 0.3 of 1 per cent, and 
with rate determination as before. The instrument is thus sufficiently sensitive 
to indicate the minimum perceptibility thresholds for either of these two types 
of modulation. 

The equipment weighs approximately 400 pounds complete, and is mounted as 
a unit upon rollers to facilitate movement to the machinery being tested. The 
appearance of the assembly is shown in Fig. 1. It is energized from a 110- volt, 
a-c. line. Six milliwatts of input signal having a frequency of approximately 3000 
cps. are required for measurement, but any other frequency between 2000 and 
4000 may be measured, provided suitable correction factors are applied. No 
other equipment than that shown is normally required, although, if desired, an 
oscillograph may be connected for further refinements of measurement. The 
instrument may be quickly and easily operated to furnish definite readings of 
the frequency distribution of flutter which may be recorded upon a chart meter 
if desired for permanent record. 

Principle of Frequency Modulation Measurement. The physical nature of fre- 
quency modulation and the relationship to flutter in sound records have been 
previously described in the literature, 1 to which reference should be made for an 
understanding of the fundamentals. The instrument herein described employs 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
May 25, 1937. 

** Electrical Research Products, Inc., Hollywood, Calif. 




[j. M. P. E. S. 

the "amplitude modulation" method of measuring frequency variation. This is 
accomplished in the following manner, as shown in Fig. 2 : 

A relatively high frequency of approximately 3000 cps. whose frequency modu- 
lation is to be determined is filtered to remove noise, then impressed upon a modu- 
lator, where it is heterodyned by a local oscillator of adjustable frequency. The 
difference frequency is transmitted through a band-pass filter, which rejects the 
unwanted modulation products so that a new wave is obtained having the same 
number of cycles variation as did the original signal, but the mean frequency of 

FIG. 1 . Laboratory flutter-measuring instrument. 

which may be set to a definite value required for measurement. This new 
wave is then impressed upon a frequency-discriminating network which con- 
verts the frequency-modulated wave into one having amplitude modulation, the 
conversion being such that the percentage of amplitude modulation obtained is 
in linear proportion to the percentage of frequency modulation and independent 
of the rate. This output is amplified, and then rectified and suitably filtered, 
to produce a d-c. component whose amplitude is proportional to the mean in- 
coming frequency, and an a-c. component which is the variation factor to be 
measured. When no separation of the latter into its individual components is to 
be made, the output is coupled by means of a transformer to a copper-oxide rec- 
tifier and thence to a milliammeter (which may be a chart meter or an ordinary 

Aug., 1937] 



meter as desired). The meter is calibrated in terms of percentage frequency 
modulation of the 3000-cycle signal, the following full-scale sensitivity ranges 
being made available : 0.1, 0.2, 0.5, and 2.0 per cent, as read on a high- 
speed movement type of volume indicator meter. Full-scale, 4 1 /2-inch deflection 
charts may be recorded with 0.5 or 2.0 per cent variations. The readings 
given are in terms of variation on each side of 3000 cps. rather than in terms of 
the total frequency change relative to the signal frequency, which is believed to 
be in line with the definition of percentage modulation used in radio and other 

To analyze the rate components in the flutter wave, a set of band-pass filters 
with adjustable transmission ranges is interposed between the demodulator and 
the above-mentioned meters. Each filter covers a rate band about one-half 
octave wide, and twelve filter combinations are used to cover the range of to 
200 cps. Table I shows the bands available. Since, for the very low frequencies 


Table of Measuring Bands and Method of Reading Charts 

Measuring Band 










Frequency Range 



34 - 
22 - 
12 - 
7 - 
1 - 
7 - 


- 80 

- 50 

- 34 

- 22 

- 12 



Method of Reading Chart 

Mean Deflections of Needle or Pen 

12 - 22 
22 - 34 

Pen Swing Peak to Peak 

Rate Observation Only 

involved, large values of inductance and capacity are required with a minimum of 
resistance dissipation, a considerable amount of investigation was required to 
produce a satisfactory coil and filter design. Rates from 2.5 to 200 per second are 
analyzed by measuring the components transmitted through the band-bass filter. 
To measure flutter rates of less than 2.5 cps., the flutter wave, itself, obtained 
by the demodulating action of the instrument, is impressed upon the chart meter 
so that it functions as an oscillograph. Low-rate variations are thus indicated by 
the swing of the writing pen, which is proportional to the incoming frequency. The 
amplitude of swing of the pen is constant for frequencies between and 1 per 
second, and by applying equalization, a range of uniform response between 1 and 
2.5 cps. is provided. These two ranges are thus pen-swing bands as distinguished 



from the other bands in which the mean deflection of the needle from zero serves 
to indicate the components passed through the band-filters. All bands may be 
converted to swing-bands by removing the rectifier and biasing out the chart pen 
so that oscillograms may be made of rates up to about 25 per second, above which 
the vibration of the pen is too greatly attenuated to produce useful information. 
This method is indicated in the last five conditions shown in Table I, and furnishes 
useful qualitative information as to the exact rates present. For oscillograms of 
frequencies in the higher rate-bands wherein the chart pen will not respond, a 
mechanical oscillograph may be externally connected to the instrument, and uni- 
form indication of the exact frequencies present in each band may be obtained. 
Satisfactory measurements can usually be obtained without so doing, however. 
Fig. 3 shows a typical flutter analysis chart made of one of the older types of 
theater reproducing machines. The percentage variation of signal frequency in 
each band is indicated by the mean deflection of the curve above the base line, the 

FIG. 2. Diagram of fluttering- measuring instrument. 

height being calibrated directly in per cent variation as shown. Thus in the 2.5 
to 4.5-cps. band a variation of approximately ==0.04 per cent is indicated. This 
rather small disturbance was due to a 3-per-second variation present in the film 
used for test, and originated with the 32-tooth sprocket of the recording machine. 
The next higher band, 4.5 to 7 cps., shows considerably greater amplitude, ap- 
proximately 0.14 per cent. This variation was a 6-per-second rate, due to 
eccentricity of the 16-tooth filtered drive sprocket, as shown in Fig. 4. The suc- 
ceeding bands indicate decreased amplitudes up to the 22- to 34-band, which rises 
to a value of 0.08 per cent. In this band the disturbing rate was 24 per second, 
corresponding to the frame speed. Thereafter the readings fall off up to the 80- 
to 130-cycle band, which rises to 0.17 per cent. In this band the predominant 
rate was 96 cps., corresponding to the number of sprocket holes engaged per 
second. The total reading at the end indicating the summation of all the com- 
ponents present shows 0.3 per cent. In Fig. 3, the readings given show only 
approximately what the disturbing rates are. The more exact rates as stated in 
connection with Fig. 3 are determined from the chart oscillograms of Fig. 4. Here 
the alternating flutter rates have been impressed directly upon the meter element 
in such a manner that the element acts as an oscillograph. The paper speed cor- 

Aug., 1937] 



responds to one second of time between each line of the chart, so that to determine 
the rate the number of wave crests per interval of time is counted. In the" upper 
left-hand chart of Fig. 4, variations between and 1 cps. are transmitted most 
effectively. Here a variation of about one per second is shown, which is due to 
the natural period of the flywheel. In the succeeding chart variations between 
1.0 and 2.5 cps. are accentuated. The next chart to the right is equalized to 
emphasize 2.5 to 4.5 cps., which is followed by oscillograms of the higher rate bands 
as marked on the charts. The 3-per-second and also the 6-per-second rates re- 
ferred to previously are plainly visible. The 24-per-second rate may be counted 
on the original chart, but probably will not be discernible in Fig. 4. 

Since the dynamic response of the writing pen is decreased rapidly for rates 
above 3 per second, there is shown a steady attenuation in amplitude as the rate 














' ~fr 















1 1 /, 


CT'^i / =*=a 

-H 1 /L^jL^^f 

/ / / / / / 

/ /- j= 
1 1 "'? /j 



80-130^ 130-2000. 2-2000. 


FIG. 3. Percentage flutter-band analysis. Percentage variation is 
proportional to amplitude above base line. 

increases, but just sufficient amplitude is obtained to determine the actual rates 
up to about 30 cps. Above this rate there is seldom a disturbing variation other 
than that of 96 per second, due to sprocket-hole propulsion. Although the oscillo- 
grams shown in Fig. 4 are used most frequently for the determination of rate, the 
first two will also indicate percentage variation within their respective bands. 
Thus in the upper left chart of Fig. 4 a variation having a peak-to-peak swing 
within the range indicated by the arrows will be 0.1 per cent for rates between 
and 0.1 cps. The amplitude of the 1-per-second variation is shown to be approxi- 
mately 0.05 per cent. The second chart of Fig. 4 may be similarly used to de- 
termine the amplitude of variations between 1.0 and 2.5 per second where such 
components occur. Thus the amplitude of extremely low-rate variations may be 
accurately measured, so that when supplemented by the percentage analysis, as 
shown in Fig. 3, all rates between and 200 per second are covered. 



Chart Mechanism. An automatic chart drive and switching system is used by 
means of which measurements of the flutter spectrum are automatically made 
throughout the range provided in the following manner: After adjusting the in- 
put signal to its proper value and operating the heterodyne condenser to obtain 
the correct measuring frequency, a switch is thrown causing a set of automatic 
switches to connect in, successively, one filter after another, and for each condition 
causing the chart motor to advance the paper for three seconds. Having gone 
through the full number of measurement bands the action stops, leaving the 
complete story written upon the chart, which the operator may examine at his 
convenience. Should the automatic feature not be desired, any filter condition 
may be manually switched in and a chart may be made or not as desired. 

The chart meter used is a commercial recording milliammeter with to 5-ma. 
scale. It is driven by a 60-cycle synchronous motor, producing a chart speed of 
3 /4 inch per second. The dynamic response of the writing pen is practically 




l =\ 











4.5-70 O 




FIG. 4. Chart oscillograms for exact rate determination. Percent- 
age not proportional to amplitude except in bands noted. 

uniform from zero to 1 .0 per second, above which the response drops off steadily, 
being about 50 per cent at 2 cps. and around 10 per cent of the static response at 

Principle of Amplitude Modulation Measurement. The method of measuring 
amplitude modulation in the original signal consists in substituting a resistance 
pad for the frequency discriminating network (Fig. 2, A -A} and proceeding as for 
flutter measurements, except that since the chart meter is insufficiently sensitive 
for this measurement a special meter is used having its scale calibrated directly in 
percentage of amplitude modulation. Full-scale indications of 3.0, 10.0, 
and 30 per cent are provided. The band-pass filters may also be employed in 
these measurements. Although amplitude modulation is not frequently a source 
of trouble in reproduction, it does occasionally occur in film recording and proc- 
essing so that there is some value in being able to measure it. 

No special provision has been made to eliminate the effect of amplitude modula- 
tion in the original signal when measuring frequency modulation. Because of 
the high conversion factor of the instrument in converting frequency modulation 
to amplitude modulation, such amplitude effects as are Initially in the signal are 
normally negligibly small compared to the converted amplitudes. As a pre- 


cautionary measure, when measuring film reproduction it is advisable to scan not 
less than 0.020 inch away from the line of sprocket holes in order to avoid the 
amplitude modulation caused by irregular development around the sprocket 
holes. 4 

Auxiliary Equipment. The accuracy of reading of the instrument is checked 
by the use of a calibration set, which generates an artificial frequency-modulated 
wave of known percentage and rate. This unit is mounted inside the doors of the 
lower part of the case, and consists of an oscillator having rotor plates driven by 
a variable-speed motor. As the plates rotate, the oscillator frequently is changed 
to the extent desired, which may be adjusted by the controls of the instrument. 
The rotor plates may be driven at any rate between Vz and 200 cps., and the 
percentage may be set for any value between 0.05 and 2.0 per cent. If the 
percentage indication of the flutter-measuring set is found to be in error, an adjust- 
ment may be readily made to correct it. However, a high degree of stability in 
the readings has been obtained so that adjustments need rarely be made. 

A secondary standard for calibrating the flutter-measuring set is provided in 
the form of a phonograph record having various percentages of frequency modula- 
tion at a 100-cps. rate. This record may be played on a moderately good turn- 
table, and calibrations are made only through the band-filter, which passes a 100- 
cps. rate. The effect of turntable irregularities is eliminated, since such varia- 
tions are generally of much lower rate than can be passed through the 100-cps. 

Measurement of flutter introduced by recording machinery is usually made by 
recording upon a film, which is subsequently reproduced and measured on a ma- 
chine as nearly flutter-free as possible. One type of equipment used for this 
purpose is a high-quality disk turntable carrying a drum around which a short 
loop of film is wound and reproduced by optical scanning. 2 

The instrument described has been in daily use for nearly a year, measuring a 
wide variety of recording and reproducing machinery for both film and disk. 
Numerous cases have occurred wherein unsuspected sources of trouble have been 
located that would probably have remained obscure without such analytical 

Although the instrument described may seem overly elaborate, the outstanding 
results obtained have more than justified its use as a laboratory tool for the de- 
velopment of new equipment and for the effective correction of faults with a 
minimum loss of time. 


1 SHEA, T. E., MACNAIR, W. A., AND SUBRIZI, V: "Flutter in Sound Records," 
J. Soc. Mot. Pict. Eng., XXV (Nov., 1935), No. 5, p. 403. 

2 SCOVILLE, R. R.: "A Portable Flutter-Measuring Instrument," /. Soc. Mot. 
Pict. Eng., XXV (Nov., 1935), No. 5, p. 416. 

3 KELLOGG, E. W., AND MORGAN, A. R.: "Measurement of Speed Fluctuations 
in Sound Recording and Reproducing Equipment," /. Acous. Soc. Amer. (April, 

4 FRAYNE, J. G., AND PAGLIARULO, V.: "The Influence of Sprocket Holes upon 
the Development of Adjacent Sound-Track Area," J. Soc. Mot. Pict. Eng., XXVIII 
(March, 1937) No., 3, p. 235. 



S. J. BEGUN** 

Experience has shown that in studying languages, elocution, singing, or other 
subjects involving the use of the voice, it is most important that the student hear a 
reproduction of his own voice. No one can hear himself as others hear him, due to 
the fact that the speaker hears his voice not so much by sound transmission 
through the air, as by bone conduction through his head. If the student could 
hear his own voice as he hears the voices of others, he could readily perceive his 
mistakes. Only by hearing a good reproduction of his voice is the student able to 
study his voice objectively and improve and train it by self -correction. 

In the past, only mechanical recording was available for voice training by self- 
correction. However, to make a disk record and play it back requires manual 
work and dexterity. In addition, each disk can be used for recording only once. 
Since voice training by self-correction requires recording and listening frequently 
to the recorded voice, a simple fool-proof recording system requiring no special 
handling and enabling unlimited use of a single sound-carrier would be ideal. 

Magnetic recording is the ideal medium for such objective voice study and 
training. A single recording medium may be used over and over again for new 
voice records. If desired, the record may be preserved and reproduced years 
later. A small magnetic recording head records and reproduces the speech with- 
out any observable change in the recording medium; the process of making a new 
record obliterates the preceding record. The speaker can hear his voice as soon 
as it is recorded, and can repeat the reproduction as many times as he desires. 
A single push-button controls all the recording and reproducing operations. A 
condensed description of the principles underlying magnetic recording has been 
described previously in the JOURNAL. 1 

A new magnetic recording machine for speech and voice training has been de- 
veloped (Fig. 1). The recording medium is formed by a helix of endless tape 150 
feet long, guided by four rollers mounted at the four corners of a frame that fits 
into a small cabinet or trunk. A spring-and-rubber mounted motor hi the bottom 
of the frame drives one of the rollers through a belt and propels the tape at a con- 
stant speed. Guide bars mounted hi front of the rollers maintain the proper 
spacing of the loops of tape on the rollers. One loop of the propelled endless tape 
is led between the two hinged halves of the small magnetic head mounted at the 
top of the frame (Fig. 2) . A pair of recording pole-pieces and a pair of obliterating 
pole-pieces are mounted side by side hi the magnetic head. A new record is made 
by the conjoint operation of the obliterating pole-pieces which erase the previous 
recording, and the recording pole-pieces, which make the new record. The re- 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
May 28, 1937. 

** New York, N. Y. 


cording pole-pieces are used for reproducing the sound. The amplifier and loud 
speaker are mounted within the frame above the motor. 

A panel on tLe front of the amplifier contains all the controls of the machine. 
One line-switch connects the line to the amplifier, and another turns the motor on 
and off. One jack provides a connection for a microphone plug or a phonograph 
plug, and another provides a connection from a phonograph pick-up. A starting 
button at the top of the panel is the sole operating control of the machine, and the 
revolving indicator knob below the starting button indicates the progress of the 
recording operation. 

The machine is designed to make a 30-second record. When the two line- 
switches are turned on, the machine reproduces, and will continuously repeat the 
recording. Recording may be effected either by inserting the microphone or 
phonograph cord plug into the proper jack. The recording is synchronous with 
the rotation of the indicator knob, which makes one revolution in 30 seconds and 
indicates upon the dial the progress of the recording. The magnetic tape, ap- 
proximately 150 feet long, is sufficient for a recording of 30 seconds, which has been 
found suitable for voice training, but longer or shorter recording periods may be 

Loud Speaker 

Recording Button 

Motor Switch 

Amplifier Switch 

. w!^m - Turntable Input 

Microphone Input 

Timing Dial 

FIG. 1. Magnetic recorder-reproducer (front view). 

provided. At the end of one revolution, the rotation of the knob is automatically 
arrested and the machine again starts the continuous reproduction of the new 

In language study it is often important to compare a sentence recorded by a 
teacher or from a phonograph record with the same sentence repeated by the stu- 
dent. This may readily be done by turning the indicator knob during the recording 
operation. During one part of the revolution of the indicator, the teacher records 
a sentence, after which the student repeats the sentence during the remaining part 
of the revolution of the indicator. If the student, after hearing the reproduced 
sentence, wishes to improve his imitation of the teacher's voice, he waits until the 
teacher's sentence is repeated by the machine, then presses the starting button, 
and repeats the recording of the sentence while the indicator moves over a part of 
the 30-second scale. As soon as the student has completed the sentence, he turns 
the indicator back to the normal reproducing position. Immediately the machine 
repeats the previously recorded sentence of the teacher, followed by the new re- 
cording of the sentence by the pupil. The student is thus abl to determine 
whether he has improved his diction, intonation, or accent, and he may do so as 
many times as he desires. 


With a high-quality microphone, a high-quality reproducer, and a suitably 
corrected amplifier, the response curve can be made uniform from 100 and 8000 
cps. The new machine is thus not only a mirror of the voice, but also an efficient 
voice teacher. However, to keep the price low and make the machine generally 

Eraser Head 

Magnetic Tape 


FIG. 2. Magnetic recorder-reproducer (rear 
view, opened). 

available for language schools and private use, the machine may be equipped with 
a carbon microphone and small loud speaker. It may also be provided with a 
loud speaker that operates as a transmitter during the recording process. 


1 BEGUN, S. J. : "Recent Developments in Magnetic Sound Recording," /. Soc. 
Mot. Pict. Eng., XXVIII (May, 1937), No. 5, p. 464. 


MR. HOPPER : What is the speed of the tape as it passes the magnetizing unit, 
what are the dimensions, and what is the volume range possible in this sort of 

MR. BEGUN: The speed of the tape is approximately five feet a second. The 
volume range is 35 decibels above the ground-noise level. The width of the tape 
is three millimeters, and the thickness 0.008 millimeter. 


It is with regret that the Society records the death of Frederick E. 
Ives, Honorary Member of the Society, and well known inventor and 
research worker in the photographic, optical, and graphic arts fields 


for man)'- years. Mr. Ives died at his home in Philadelphia on May 
28th. He was 81 years of age. A son, Dr. Herbert E. Ives, of the Bell 
Telephone Laboratories, survives. 

Mr. Ives was born February 17, 1856, in the little village of Litch- 



field, Conn. When he was 11 years of age his father died, and he was 
compelled to leave school and contribute to the support of his mother, 
two younger brothers, and two sisters. For some time he was en- 
gaged as a printer's devil in the office of the Litchfield "Inquirer." 
Although his early schooling was meager, he soon acquired an interest 
in optical and photographic subjects and began his long period of in- 
vention when still in his teens. 

While serving his apprenticeship in the printing office, he turned his 
attention to photography and in 1875-78 was in charge of the photo- 
graphic laboratory of Cornell University. During his four years at 
the institution, he perfected a process of making photoengraved typo- 
graphic printing plates from pen drawings. He also invented the 
first halftone process that was developed commercially, making by an 
ingenious and scientific procedure, plates identical in characteristics 
to those used today, but stereotype instead of copper or zinc etchings. 

In 1879 he became associated with the firm of Crosscup & West, 
wood engravers of Philadelphia, for whom he set up an establishment 
for producing photoengravings according to his process. During that 
time, also, Mr. Ives developed the ether saturator an intense light- 
source which was first used in the projection lantern at the Franklin 
Institute at Philadelphia, and for the invention of which he was 
granted the medal of the Institute. 

His inventions and practical developments in the field of photo- 
engraving probably constitute Ives' greatest claim to fame, since the 
enormous photoengraving industry of the present day derives directly 
from his establishment in Philadelphia. His first process (1878) pro- 
duced the graduation of line and dot through the use of a gelatin 
relief and an inked stippled surface pressed against it. This process, 
the first commercially successful halftone, he later (1885) superseded 
by the optical method, using a cross-line screen, which is now uni- 
versally employed. 

Ives' work in color photography began about 1885, when he first 
developed a practical method of color sensitizing, using cosine to- 
gether with chlorophyll, to equalize the color-sensitivity of the plate. 
Next came the development of trichromatic halftones by the additive 
process, which resulted in the Ives Kromskop System. Various 
medals and other honors were awarded to Ives for these inventions. 
In addition to his work on the photochromoscope system and color 
print processes, Ives is credited with the first original work on the 
modern type of binocular microscope. 


In 1905 he developed the Tripak System of color photography for 
amateur and professional photographers, and about the same time 
produced his "universal colorimeter" and "tint photometer," intended 
for industrial standardization and designation of colors. 

One of Ives' inventions best known by those in the motion picture 
field was his parallax stereogram for viewing photographic objects in 
relief without using a stereoscope. In the field of color cinematog- 
raphy, Ives has about twenty patents to his credit, resulting mainly 
from his desire to produce colored pictures on regular single-coated 
positive film. More than seventy patents were filed by him up to 
1925, but in addition, many other inventions and ideas that were not 
patented have been described by him in the literature, or have been 
utilized by others. 

From these early days, which have been sketched here very briefly, 
the life of Frederick E. Ives was filled with scientific achievement in all 
directions. The art owes much to Frederick E. Ives, and the Society 
deeply mourns the loss of such a brilliant thinker, inventor, and pro- 
fuse contributor to the arts of civilization. 



The editors present for convenient reference a list of articles dealing with subjects 
cognate to motion picture engineering published in a number of selected journals. 
Photostatic copies may be obtained from the Library of Congress, Washington, D. C., 
or from the New York Public Library, New York, N. Y. Micro copies of articles 
in those magazines that are available may be obtained from the Library of the U. S. 
Department of Agriculture, Washington, D. C. 

Academy of Motion Picture Arts and Sciences, Technical Bulletin 

(June 8, 1937) 

Revised Standard Electrical Characteristic for Two- 
Way Reproducing Systems in Theaters (p. 1). 

(June 15, 1937) 

Second Annual Report on Television from the Stand- 
point of the Motion Picture Producing Industry 

American Cinematographer 

18 (June, 1937), No. 6 

Technicolor Bringing New Charm to Screen (p. 234). W. STULL 
Erickson Describes Triple Five-Studio Spot (p. 238). C. R. EKICKSON 
Build Fastest Sky Camera to Shoot Eclipse (p. 252). 

Educational Screen 

16 (June, 1937), No. 6 
A New Era in Visual Methods (p. 182). J. B. MACHARG 


10 (June, 1937), No. 6 
I. R. E. Sees Projection Television (p. 7). 
Television Terminology (p. 14). 

Class A Push-Pull Calculations (p. 18) E. W. HOUGHTON 

For Engineer-Photographers Only (Timing Control 

Relay) (p. 22). D. G. FINK 

An Amplifier without Phase Distortion (p. 26). 

Journal of the Association of Cine Technicians 

3 (June- July, 1937), No. 10 

Evolution: A Peep into the Past (p. 41). C. FRIESE-GREENE 

The Visatone System of Sound Recording (p. 47). H. J. ROUND 

Journal of the Optical Society of America 

27 (June, 1937), No. 6 

Colorimetry: Preliminary Draft of a Report on No- 
menclature and Definitions (p. 207). L. A. JONES 



Kinematograph Weekly 

243 (May 27, 1937), No. 1571 

Printing with Non-Slip Apparatus R.C.A. Model 
(p. 53). R. H. CRICKS 

La cinematographic frangaise 

19 (May 28, 1937), No. 969 
A New Ideal Portable Block Projector (Le nouveau 

block projecteur ideal portatif) (p. ix). J. TURQUAN 

Semi-Rotating Turret and Automatic Loading Two 
Innovations in the New Paillard Cine Camera (La 
tourelle demi-ronde et le chargement automatique, 
deux innovations de la nouvelle cine-camera) (p. xvi). H. PAILLARD 

La technique cinematographique 

9 (May, 1937), No. 77 

Photographing the Interior of the Human Body 
(Prises de vues a 1'interieur du corps humain) 
(p. 929). H. GRAU 

Optical Systems for Sound Films (L'eclairage du film 

dans le lecteur de son) (p. 939). J. P. CORTET 

Motion Picture Herald (Better Theaters Section) 

127 (June 26, 1937), No. 13 

Theater Acoustics Today: 2. Design and Construc- 
tion II (p. 31). C. C. POTWIN 

Photographische Industrie 

35 (June 9, 1937), No. 23 
Stereoscopic Projection with Polarizers (Raumlicher 

Bildwurf mit Polarisatoren) (p. 639). BURKERT 

Science et industries photographiques 

Series 2, 8 (April, 1937), No. 4 

Active Atomic Groups in Color Sensitizing with Ery- 
throsine (Les groupements atomiques actifs dans la 
sensibilisation chromatique par 1'erythrosine) (p. 97). G. SCHWARZ 
Adherence of the Photographic Emulsion to a Cellulose 
Acetate Support (Adherence de 1'emulsion photo- 
graphique aux supports d'acetate de cellulose) 
(p. 99). A. CHARRIOU 


Radio Engineering 

17 (June, 1937), No. 6 

Retarding Undesired Emission in Vacuum Tubes (p. 7). B. H. PORTER 
Recent Tube Developments (p. 13). 
Distortion in High-Fidelity Audio Amplifiers (p. 16). R. LEE 




Officers and Committees in Charge 

W. C. KUNZMANN, Convention Vice-President 

J. I. CRABTREE, Editorial Vice-President 

S. K. WOLF, President 

O. M. GLUNT, Financial Vice-President 

G. E. MATTHEWS, Chairman, Papers Committee 

G. FRIEDL, Chairman, Atlantic Coast Section 

Local Arrangements and Reception Committee 

G. FRIEDL, JR., Chairman 






Registration and Information 

W. C. KUNZMANN, Chairman 

Ladies' Reception Committee 

MRS. S. K. WOLF and MRS. O. F. NEU, Hostesses 



Banquet Committee 

A. S. DICKINSON, Chairman 




Publicity Committee 

W. WHITMORE, Chairman 





Projection Committee 

H. GRIFFIN, Chairman 




Officers and Members of New York Projectionists Local 306, I. A. T.S. E. 

Membership Committee 

E. R. GEIB, Chairman 



Hotel Accommodations 

O. F. NEU, Chairman 




The headquarters of the Convention will be the Pennsylvania Hotel, where ex- 
cellent accommodations have been assured and a reception suite will be provided 
for the Ladies' Committee. An excellent program of entertainment will be ar- 
ranged by the hostesses. 

Special hotel rates guaranteed to SMPE delegates, European plan, will be 
as follows: 

One person, room and bath $3 . 50 
Two persons, double bed and bath 5 . 00 

Two persons, twin beds and bath 6 . 00 

Parlor suite, one person 11 .00 up 

Parlor suite, two persons 13. 00 up 

Room reservation cards will be mailed to the membership of the Society in the 
near future, and everyone who plans to attend the Convention should return his 
card to the Hotel promptly in order to be assured of satisfactory accommodations. 
Consult your local railroad ticket agent with regard to coach and pullman rates. 

Parking accommodations will be available to those who motor to the Conven- 
tion at the fire-proof garage of the Hotel, at the rate of $1 .25 for twenty-four hours 
or $1.00 for twelve hours, including pick-up and delivery at the door of the Hotel; 
weekly rate, $7.50. 

Technical Sessions 

An attractive program of technical papers and presentations is being arranged 
by the Papers Committee. All technical sessions, apparatus symposiums, and 
film programs will be held in the Salle Moderne of the Hotel, on the eighteenth 

There will be no general Apparatus Exhibit, but those who have developed new 
equipment during the past year are invited to submit technical descriptions of it 
to the Papers Committee for possible inclusion in the Apparatus Symposium. 



Registration headquarters will be located on the eighteenth floor of the Hotel at 
the entrance of the Salle Moderne, where the technical sessions will be held. Ex- 
press elevators from the lobby will be reserved for the Convention. All members 
and guests attending the Convention are expected to register and receive their 
badges and identification cards required for admission to certain evening sessions 
of the Convention, as well as to various de luxe motion picture theaters that will 
honor the cards as courtesy admissions. 

Luncheon and Banquet 

The usual informal get-together luncheon will be held at noon on October llth 
in the Roof Garden of the Hotel, and the semi-annual banquet and dance will 
take place on the evening of October 13th. 

Addresses will be delivered by prominent members of the industry on both 
occasions. At the banquet the annual presentation of the SMPE Progress Medal 
and the Journal Award will be made, and the officers-elect for 1938 will be intro- 
duced. The banquet will conclude with dancing and entertainment. 

Tickets for admission to the informal luncheon and the banquet may be ob- 
tained at the registration desk. Banquet tables reserved for 8, 10, and 12 per- 

Ladies' Program 

An especially attractive program for the ladies attending the Convention is 
being arranged by Mrs. S. K. Wolf and Mrs. O. F. Neu, Hostesses, and the Ladies' 

A suite will be provided at the Hotel, where the ladies will register and meet for 
the various events on their program. Further details will be published in a suc- 
ceeding issue of the JOURNAL. 

Entertainment and Diversion 

Golfing privileges may be arranged at several country clubs in the vicinity of 
New York, as well as various tours to points of interest in and about the city. 
These arrangements may be made either at the Convention registration desk or 
through the management of the Hotel. 



At a meeting held at the Hotel Pennsylvania, New York, N. Y., on July 9th, 
nominations of officers for 1938 were completed by the Board of Governors. 
Announcement of the nominees will be made as soon as all the acceptances have 
been received. Ballots will be mailed to the voting membership on or about 
September 2nd, and the results of the election will be announced at the Fall Con- 
vention on October llth. The officers-elect will assume office on January 1st. 

The report of finances submitted by Mr. O. M. Glunt, Financial Vice-President, 
indicated that although conditions were satisfactory, quite a number of members 
have not yet paid their 1937 dues. A third dues notice is being mailed to each 
delinquent member at the time this issue goes to press, and all who have not paid 
their dues so far are urged to do so immediately. 

Committees and other details relating to the approaching Fall Convention, as 
described in the preceding section of this issue of the JOURNAL, were announced 
by Mr. W. C. Kunzmann, Convention Vice-President, and arrangements are being 
made to gather an interesting selection of technical papers and presentations 
under the direction of Mr. J. I. Crabtree, Editorial Vice-President. 


A new negative has just been completed for the 35-mm. sound test -film, re- 
corded by the ultraviolet-light system. The contents of the film are identical with 
those of the preceding negative, except that new and more appropriate musical 
selections and voices have been chosen. The test-film was originally described in 
the August, 1933, issue of the JOURNAL, p. 89. Some details of the contents of 
the films are given in the advertisement on a following page. 

In addition, a 16-mm. sound test-film has been prepared, the contents being 
identical with those of the 35-mm. sound test -film, except that the frequency range 
and the series of fixed frequencies extend to 6000 cycles instead of to 10,000. 

The complete set of test-films available at the prices stated is as follows : 

(1) 35-mm. sound test-film $37.50 

(2) 35-mm. visual test-film 37.50 
(5) 16-mm. sound test-film 25.00 
(4) 16-mm. visual test-film (optical reduction of the 35-mm. visual 

test-film) 25.00 


At a recent meeting of the Admissions Committee, at the General Office of the 
Society, the following applicants for membership were admitted to the Associate 
grade : 




[J. S. M. P. E. 

ALAG, S. S. 

Murtiza Pore (Berar), 


P. O. Box 63, 

North Hollywood, Calif. 
706 W. Grand Ave., 

Oklahoma City, Okla. 

831 N. Rose Ave., 
Burbank, Calif. 
Via Saturnia, 29, 


5228 De Lonpre Ave., 

Hollywood, Calif. 

RCA Manufacturing Co., Inc., 
1016 N. Sycamore Ave., 
Hollywood, Calif. 
2468 Lyric Ave., 

Los Angeles, Calif. 
1646 S. Olive St., 

Los Angeles, Calif. 
231 Clinton Heights Ave., 
Columbus, Ohio. 


5611 Carlton Way, 
Hollywood, Calif. 
645 N. Martel, 

Hollywood, Calif. 
1216 Burrard St., 

Vancouver, B. C. 
Hawkins, J. N. A. 
2807 Eighth Ave., 

Los Angeles, Calif. 

24 Murriverie Road, 
North Bondi, 
New South Wales, 

1935 Del Mar Ave., 

Wilmar, Calif. 

24 East Newell Ave., 

Rutherford, N. J. 

7510 Claybeck Ave., 

Burbank, Calif. 
305 Dundas St., W., 
Toronto, Ontario, 

University of Minnesota, 

Minneapolis, Minn. 
10,820 Morrison St., 

North Hollywood, Calif. 

Hans H. Knutsen & Co., 
Munkedamsveien 35, 
Oslo, Norway. 

176 Clarkson Ave., 
Brooklyn, N. Y. 
LAY, F. L. 

1961 S. Vermont Ave., 

Los Angeles, Calif. 

Studios and Laboratory, 
179 Inverness, 
P. O. Box 411, 
Manila, P. I. 
1343 N. Citrus, 

Hollywood, Calif. 
PILTZ, C. A., 
39 Oxford St., 

Newark, N. J. 

604 N. Walden Drive, 
Beverly Hills, Calif. 

Technicolor Motion Picture Corp. 
Drawer 791, 
Hollywood, Calif. 

Aug., 1937] 



1438 E. 18th St., 

Los Angeles, Calif. 

Calle F. Lacroze 2176, 

Buenos Aires, Argentina. 

824V2 N. Las Palmas Ave., 

Hollywood, Calif. 

Afifa, Viktoriastrasse, 
Berlin, Germany. 

Smith Theatre Supply, 
617 First Ave., 
Spokane, Washington. 

101 N. Kenmare Ave., 

Los Angeles, Calif. 

4207 Brighton Ave., 
Los Angeles, Calif. 
243 Oakland Ave., 
Oakland, Calif. 


Batten, Barton, Durstine & Osborn, 
383 Madison Ave., 
New York, N. Y. 
5127 Eleventh Ave., 
Los Angeles, Calif. 
16 Clifton Ave., 
New South Wales, 

4601 Sunset Blvd., 
Hollywood, Calif. 

845 South Manhattan Place, 

Los Angeles, Calif. 
WORK, L. P. 

532 Fourth Ave., 
Clinton, Iowa. 

6013 29th Ave., N. E., 
Seattle, Washington. 

359 Ft. Washington Ave., 
New York, N. Y. 

In addition, the following applicants have been admitted by vote of the Board 
of Governors to the Fellowship (F) and Active (M) grades: 

Cinaudagraph Corp., 
2 Selleck St., 
Stamford, Conn. 
FRIEND, H. H. (F) 
Cinaudagraph Corp., 
2 Selleck St., 
Stamford, Conn. 
BOYER, M. R. (M) 

Du Pont Film Mfg. Corp., 

Parlin, N. J. 

Electrical Research Products, Inc., 
7046 Hollywood Blvd., 
Los Angeles, Calif. 

HARPER, P. F. (M) 

821 N. Poinsettia Place, 

Hollywood, Calif. 
General Delivery, 

Los Angeles, Calif. 

Dominion Sound Equipments Ltd. 
1620 Notre Dame St., 
W. Montreal, 
Quebec, Canada. 

Hollywood Camera Exchange, 
1600 Cahuenga Blvd., 
Hollywood, Calif. 

S. M. P. E. 


These films have been prepared under the supervision of the Projection 
Practice Committee of the Society of Motion Picture Engineers, and are 
designed to be used as precision instruments in theaters, review rooms, 
exchanges, laboratories, factories, and the like for testing the perform- 
ance of projectors. 

Only complete reels, as described below, are available (no short sections 
or single frequencies). The prices given include shipping charges to all 
points within the United States ; shipping charges to other countries are 

35-Mm. Sound-Film 

Approximately 500 feet long, consisting of recordings of several speak- 
ing voices, piano, and orchestra; buzz- track; fixed frequencies for focus- 
ing sound optical system; fixed frequencies at constant level, for de- 
termining reproducer characteristics, frequency range, flutter, sound- 
track adjustment, 60- or 96-cycle modulation, etc. 

The recorded frequency range of the voice and music extends to 10,000 
cps. ; the constant-amplitude frequencies are in 15 steps from 50 cps. to 
10,000 cps. 

Price $37.50 each, including instructions. 

35-Mm. Visual Film 

Approximately 500 feet long, consisting of special targets with the aid 
of which travel-ghost, marginal and radial lens aberrations, definition, 
picture jump, and film weave may be detected and corrected. 

Price $37.50 each, including instructions. 

16-Mm. Sound-Film 

Approximately 400 feet long; contents identical to those of the 35-mm. 
sound-film, with the exception that the recorded frequency range ex- 
tends to 6000 cps., and the constant-amplitude frequencies are in 11 
steps from 50 cps. to 6000 cps. 

Price $25.00 each, including instructions. 

16-Mm. Visual Film 

An optical reduction of the 35-mm. visual test-film, identical as to 
contents and approximately 400 feet long. 
Price $25.00 each, including instructions. 







Volume XXIX SEPTEMBER, 1937 Number 3 



Recent Progress in Acoustics V. O. KNUDSEN 233 

The New Agfacolor Process. . . J. L. FORREST AND F. M. WING 248 
The RCA Recording System and Its Adaptation to Various 

Types of Sound-Track G. L. DIMMICK 258 

A Device for Direct Reproduction from Variable- Density Sound 

Negatives W. J. ALBERSHEIM 274 

An Automatic Sound-Track Editing Machine G. M. BEST 281 

A Dubbing Rehearsal Channel H. G. TASKER 286 

The Evolution of Special-Effects Cinematography from an 

Engineering Viewpoint F. W. JACKMAN 293 

Present Aspects in the Development of 16-Mm. Sound 

New Motion Picture Apparatus 

Improved Noise-Reduction System for High-Fidelity Re- 


Two New Films for Duplicating Work 


Infrared Negative as Applied to Special-Effects Photography 


Current Literature 330 

Book Review 332 

Committees 334 

Fall, 1937, Convention; Hotel Pennsylvania, New York, N. Y., 

October ll-14th 339 

Society Announcements 343 





Board of Editors 
J. I. CRABTREE, Chairman 



Subscription to non-members, $8.00 per annum; to members, $5.00 per annum, 
included in their annual membership dues; single copies, $1.00. A discount 
on subscriptions or single copies of 15 per cent is allowed to accredited agencies. 
Order from the Society of Motion Picture Engineers, Inc., 20th and Northampton 
Sts., Easton, Pa., or Hotel Pennsylvania, New York, N. Y. 
Published monthly at Easton, Pa., by the Society of Motion Picture Engineers. 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General and Editorial Office, Hotel Pennsylvania, New York, N. Y. 

West-Coast Office, Suite 226, Equitable Bldg., Hollywood, Calif. 
Entered as second class matter January 15, 1930, at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. Copyrighted, 1937, by the Society of 
Motion Picture Engineers, Inc. 

Papers appearing in this Journal may be reprinted, abstracted, or abridged 
provided credit is given to the Journal of the Society of Motion Picture Engineers 
and to the author, or authors, of the papers in question. Exact reference as to 
the volume, number, and page of the Journal must be given. The Society is 
not responsible for statements made by authors. 


President: S. K. WOLF, 100 E. 42nd St., New York, N. Y. 
Past-President: H. G. TASKER, Universal City, Calif. 

Executive Vice-President, G. F. RACKETT, 823 N. Seward St., Hollywood, Calif. 
Engineering Vice-President: L. A. JONES, Kodak Park, Rochester, N. Y. 
Editorial Vice-President: J. I. CRABTREE, Kodak Park, Rochester, N. Y. 
Financial Vice-President: O. M. GLUNT, 463 West St., New York. N. Y. 
Convention Vice-President: W. C. KUNZMANN, Box 6087, Cleveland, Ohio. 
Secretary: J. FRANK, JR., 90 Gold St., New York, N. Y. 
Treasurer: L. W. DAVEE, 250 W. 57th St., New York, N. Y. 


M. C. BATSEL, Front and Market Sts., Camden, N. J. 

A. S. DICKINSON, 28 W. 44th St., New York, N. Y. 

G. FRIEDL, JR., 25 Hunter Ave., Fanwood, N. J. 

A. N. GOLDSMITH, 444 Madison Ave., New York, N. Y. 

H. GRIFFIN, 90 Gold St., New York, N. Y. 

A. C. HARDY, Massachusetts Institute of Technology, Cambridge, Mass. 

K. F. MORGAN, 7046 Hollywood Blvd., Los Angeles, Calif. 

C. H. STONE, 205 W. Wacker Drive, Chicago, 111. 


Summary. Some recent developments in acoustics, especially in Germany, 
Russia, and in the author's laboratory, are reviewed. Experiments by E. Meyer, 
of Berlin, help to clarify the differences between geometrical and diffuse reflections 
of sound in rooms, and reveal the nature of some of the errors inherent in reverbera- 
tion measurements. Meyer also describes special absorbent materials, as thin wood 
panelling or stretched oilcloth, which are selectively absorbent for low frequencies. 
S. Rschevkin, of Moscow, describes a method for prolonging, diminishing, or other- 
wise modifying the reverberation in a room by means of Helmholtz resonators. 

A new electrodcoustical device for the artificial production of vowels, by K. W. 
Wagner, of Berlin, is capable of generating typical German vowels that can not be 
distinguished from the originals. The oscillogram and sound spectrum of the arti- 
ficial vowel resemble more closely the oscillogram and sound spectrum of the original 
vowel than do two sets of oscillo grams and sound spectra of the same vowel "picked 
up" at two different microphone positions in the same room. The experiments 
reveal the nature of sound distortion caused by reflections from the boundaries of a 
room, and show that the ear tolerates considerable distortion. 

The paper concludes with a review of some recent work undertaken by the writer, 
including resonance in rooms, the acoustical design of broadcasting studios, and 
vistas in musical acoustics. 

It is the purpose of this paper (a) to review some recent advances of 
acoustics in foreign countries, and (b) to describe briefly some acous- 
tical experiments now in progress at the University of California at 
Los Angeles. 

Acoustical research in Germany, especially as applied to buildings, 
is largely concentrated in one place, the Institute for Vibration Re- 
search, in Berlin. Much of this work has been done by E. Meyer and 
his associates, under the direction of K. W. Wagner, the Director of 
the Institute. 


Meyer 1 has investigated the nature of the reflection of sound in 
rooms by comparing the differences in the distribution of light in small 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received 
May 26, 1937. 

** University of California, Los Angeles, Calif. 


234 V. O. KNUDSEN [j. S. M. p. E. 

optical chambers for specular and for diffuse reflection from the 
boundaries of the chamber. The calculation of the reverberation 
time in rooms is based upon a theory that assumes diffuse reflection, 
whereas the materials ordinarily used for the boundaries of a room 
give rise to reflections that are chiefly "specular." Meyer made 
measurements of the absorption of light inside a so-called "Ulbricht" 
ball, which is an optical chamber with boundaries that reflect light 
diffusely. It is not practicable to measure the "reverberation time" 
for light in such a chamber, since the rate of decay of the light 
is so very fast. However, it is practicable and relatively simple, to 
measure the average intensity of light in the chamber, first when the 
Ulbricht ball is empty, and afterwards with a certain area of absorp- 
tive material (paper) inside the chamber. The theory of Ulbricht is 
similar to that of Sabine or Eyring, that is, the total absorption of the 
chamber is inversely proportional to the average intensity of light 
within the chamber. Meyer reports that the absorption of the added 
piece of paper was completely independent of the position of the piece 
of paper inside the Ulbricht ball, but that the measured absorption of 
the paper varied enormously when similar measurements were made 
in a chamber that reflected light specularly. Meyer reports also that 
the measured coefficient of absorption of the piece of paper was inde- 
pendent of its size (the area varied in the ratio of one to one hundred) , 
as measured in the Ulbricht ball. 

These results indicate that we should use reverberation chambers 
with diffusely reflecting boundaries, if we expect to obtain reliable 
coefficients of sound absorption by means of the reverberation equa- 
tions that are commonly used in practice. Meyer has made acous- 
tical measurements in the chamber shown in Fig. 1, and found that 
the results of sound absorption measurements, at a frequency of 
7000 cps., depended much less upon the position of the material, and 
upon its size, than was the case when the boundaries of the chamber 
were smooth. It is obvious, however, that it would be impracticable 
to provide such chambers for low frequencies even of the order of 
100 cps., where the irregularities of the surface would have to be of 
the order of ten to twenty feet. 

For several years the writer and several of his pupils have investi- 
gated the possibility of measuring sound absorption coefficients of 
acoustical materials by using the intensity method instead of the de- 
cay method. Using a constant source of sound in the chamber, the 
average intensity of the steady state is measured first with the room 

Sept., 1937] 



empty and then with the absorptive material in the room. In some 
preliminary experiments it was found that the absorption coefficient 
of Acousti-Celotex was essentially independent of the area of the 
sample from an area of four square-feet up to an area of 144 square- 
feet. The intensity method of measuring sound absorption involves 
many difficulties in the technic of measurement, but both the theory 
and the preliminary measurements indicate that we should be able to 

FIG. 1. View of reverberation chamber with bound- 
aries that reflect high-frequency sound (7000 cps.) dif- 
fusely. (E. Meyer) 

obtain more reliable coefficients of sound absorption by this method 
than we can by the reverberation method. 


Cammerer and Durhammer 2 find that there is an optimal separa- 
tion between double partitions, for the insulation of sound. Their 
results are particularly applicable to the use of double windows be- 
tween studios and monitor or control rooms. Fig. 2 shows the trans- 
mission loss due to the air-space, as a function of the width of the air- 
space between the two partitions, for a frequency that is the geomet- 
rical mean of the frequency range of 100 to 3000 cps. It will be seen 
that the optimal separation is ten centimeters. This, of course, ap- 
plies for the frequency of 547 cps., that is, the geometrical mean of 100 
and 3000. Meyer and others have shown that the transmission loss 



[J. S. M. P. E. 

can be increased by introducing absorptive material into the air- 
space around the edges that separates the two partitions. This ab- 
sorptive material increases the damping for any natural frequencies 
or "eigentones" within the air-space, and thereby reduces the coup- 
ling between the two partitions. If it is desired to obtain the optimal 
transmission loss at frequencies lower that 547 cps., the separation of 
the two partitions should be greater than ten centimeters. For fur- 

6 8 10 12 W 16 18 20cm 

FIG. 2. Sound insulation attributable to air- 
space between double partitions, for a frequency 
of 547 cps. (Cammerer and Durhammer) 

ther details, the article by Cammerer and Durhammer should be 


It is not generally appreciated by acoustical engineers that a small 
opening transmits very much more sound energy than would be cal- 
culated upon the assumption that the total flux of energy through the 
opening is equal to the product of the sound intensity / times the area 
of the opening A . The actual flux of sound energy through the open- 
ing is klA, where k is a constant that depends upon the size and shape 
of the opening and upon the wavelength of the sound. Wintergerst 
and Knecht, following the theory of Lord Rayleigh, have made mea- 
surements of the transmission of sound through small circular and 
rectangular openings. For a small circular aperture, of the order of 
three to twelve millimeters in diameter, their measurements agree 


with the Rayleigh diffraction theory. The results are given as 
follows : 

Frequency 100 200 400 800 1200 1600 

k 75 56 29 12 6 2.5 

For an opening 71 millimeters long, and of different widths as indi- 
cated in the table, they obtained, at a frequency of 800 cps. : 

Slit width (mm.) 0.1 0.2 0.5 1.0 2.0 3.0 

k 300 200 100 64 38 33 

The dependence of k upon the frequency is approximately the s. me for 
rectangular openings as for circular apertures. These results are 
significant to the acoustical engineer not only in sound insulation but 
also in the design of sound absorbent materials the excess of sound 
energy transmitted through the openings is "absorbed" from the in- 
cident sound-waves. 


It is well known that the ancient Greeks attempted to improve the 
acoustics of their open-air theaters by distributing a large number of 
bronze vessels, fashioned into resonators, in regularly spaced niches 
throughout the seating area of the theater. These resonators were 
carefully tuned to respond to the various notes of musical systems 
and thereby would emphasize the more important frequency com- 
ponents of speech and music, and would particularly emphasize 
those notes in music that correspond to the harmonic scale. It is not 
improbable that these resonators would contribute some value to 
speech and music, in emphasizing the particular frequency compo- 
nents that are harmonious in music and contribute most to the intel- 
ligibility of speech. Somewhat similar resonators, or sound-boxes, 
are used in old Byzantine and Russian churches. Rschevkin 3 has 
treated theoretically this problem of resonators in rooms, and shows 
that such a system of resonators in a room increases (1) the effective 
volume of the room, and (2) the effective absorption of the room. If 
the damping in the necks of the resonators is small, the volume effect 
predominates, and the apparent reverberation time in the room is 
increased especially for frequencies near the natural frequency or 
frequencies of the resonators. If the absorption in the necks of the 
resonators is large, the absorption effect predominates, and the appar- 
ent reverberation time in the room is diminished for frequencies that 
are near the natural frequency or frequencies of the resonators. By 



[j. s. M. p. E. 

means of such resonators it is possible to control the reverberation 
characteristics of a room especially to reduce the reverberation at 
low frequencies, which is often desirable in studios treated with such 
materials as porous or fibrous plasters, felts, tiles, etc. Rschevkin 
tested this theory by placing eighty milk bottles upon the floor of a 
small room. The apparent reverberation time was increased from 
0.48 to 0.93 second for frequencies near the resonance frequencies of the 

1 3 S T t H 

FIG. 3. Oscillograms and sound spectra of the German vowel a spoken nine 
times in succession by the same speaker. (K. W. Wagner) 

bottles about 230 cps. However, this prolonged reverberation was 
due almost entirely to two rates of decay of sound in a room. The 
decay during the first 30 db. was very little influenced by the resona- 
tors, and it is this portion of the decay in rooms that is most signifi- 
cant in determining the acoustical effects; only the latter part of the 
decay was prolonged by the influence of the resonators. The observed 
effects are explained upon the basis of a coupled system of room and 
resonators. The bottle resonators had relatively little damping in 


the necks, and consequently their chief effect was to increase the re- 
verberation time for frequencies near the resonance frequency of the 
bottle, although at frequencies far removed from the resonance fre- 
quency there was a small reduction in the measured reverberation 
time in the room. 

Rschevkin describes another form of resonator, made by one of his 
colleagues, Astzifrov. These resonators consisted of circular disks of 
plywood, fastened to the walls by means of a screw at the center. 
The disks were 80 centimeters in diameter, and were held approxi- 
mately three centimeters from the wall by means of a short piece of 
wood through which the screw passed before it reached the wall. 
These disks increased very appreciably the total absorption in the 
room, although the effect was quite selective at the resonance fre- 
quencies of the disks. 

Similar resonance effects have been long observed in the cases of 
furred-out plaster, wood sheathing, etc. For example, a half-inch of 
acoustical plaster applied to a hard, rigid surface, such as concrete, 
brick, or other masonry, has an absorption coefficient of only 0.08 to 
0.10 at 128 cps. and increases to 0.30 or even higher, at high frequen- 
cies; whereas this same plaster when applied to scratch and brown 
coats over metal lath will give an almost uniform absorption over a 
relatively wide range of frequency. It is quite probable that materials 
of this type, utilizing the principles of flexural resonance, and an 
appropriately designed network of pores in the absorptive material, 
would result in an absorption characteristic that would be ideal for 
controlling the reverberation characteristics in all rooms or studios. 


K. W. Wagner 4 has developed a new electrical apparatus for the 
artificial production of vowels. The apparatus consists of an impulse 
oscillator that provides a wave-form very rich in harmonics, and a 
series of five low-pass or band-pass filters in which the cut-off fre- 
quencies and the sharpness of tuning can be controlled. A typical 
German vowel is first analyzed into its frequency components. It is 
then synthesized artificially by means of the apparatus just described. 
It is possible artificially to produce vowels that are indistinguishable 
from the originals after which they were modeled. There is a closer 
resemblance between the original and artificial vowels than there is 
between the same vowel spoken by the same person twice in succes- 
sion, or between the same vowel as detected in two parts of a room by 



[j. S. M. P. E. 

high-quality recording apparatus. The oscillograms of typical Ger- 
man vowels, and their frequency analyses, are among the best that 
have yet been produced. The experiments reveal the nature of sound 
distortion introduced by the acoustical properties of a room, such as 
boundary reflection and resonance effects; they also show that the 


1 3 5 7 9 11 13 15 

Dem Lautsprecher ajgefuhrtes Spektrum 





n n 15 17 

1 3 5 7 3 fl 13 IS 


1 3 S 7 9 11 13 15 ff 

GroBer Lautsprecher L 


1 3 S 7 9 ft 13 15 

Kleiner Lautsprecher ff 

FIG. 4. Sound spectra of the same vowel, recorded 
at three different positions in the same room. At top 
is the spectrum of the input to the loud speaker. The 
spectra at the left are for a large loud speaker; those 
at the right for a small loud speaker. (K. W. Wagner) 

ear tolerates considerable distortion, without detecting it. 
4, and 5, reproduced from Wagner's article.) 


(Figs. 3, 

Some experiments the writer conducted in 1932 demonstrated that 
reverberation consists of the damped free vibrations (or eigentones) 
of a room. 5 The frequencies n of the eigentones of a rectangular room 
are given by the Rayleigh formula : 

Sept., 1937] 



where c is the velocity of sound; /i, /s, and / 3 are the dimensions of the 
room; and p, q, and r are integers, 1, 2, 3, ... Both the steady- 
state distribution of sound in a room and the nature of the free decay 
of sound in that room are very much affected by these eigentones and 
by the exact location and directional characteristics of the source of 
sound in that room. Unfortunately, the formulas we ordinarily use 
for calculating intensity distribution and reverberation do not take 










I i . . , 


1 3 5 7 9 ti 13 














5 7 9 V 13 15 

FIG. 5. Oscillograms and sound spectra of the German vowel i (top) and 
its artificial reconstruction (bottom). (K. W. Wagner) 

into account these pertinent properties, and as a result we find many 
serious discrepancies between the calculated values of intensity dis- 
tribution or reverberation and the observed values. For example, 
the writer found that when the ceiling of a small room 8 by 8 by 9.5 
feet, was covered with a highly absorptive material, the measured 
time of reverberation at 512 cps. was 1.54 seconds; whereas the value 
calculated by the usual reverberation formula was only 0.61 second. 
The eigentones, which depended solely upon horizontal motion, 
were only slightly damped by the absorptive material in the ceiling, 
and consequently persisted for a much longer time than would be pre- 
dicted by a formula based upon diffuse sound and boundaries of uni- 



[J. S. M. p. E. 

form absorptivity. By removing approximately two-thirds of the 
absorptive material from the ceiling and applying it to two adjacent 
walls, there was reasonably good agreement between calculated and 
measured times of reverberation. In general, it is desirable to dis- 
tribute the absorptive material in a room, especially in a small room, 
so that the rate of decay will be approximately the same in all direc- 
tions. This not only makes the measured reverberation approximate 
the calculated value, but also contributes to better acoustics. 

*2 74 3 83 i 166 

159 133 56 3 73 142 147 

83 67 24 3 33 12 82 

, rui , 

3 3 3 fM 3 3 3 

3 3 3 

3 3 3 UJI 3 3 3 

190 150 60 3 Si MO WS 

83 69 26 3 4O 68 103 


99 79 32 3 36 89 109 
76 59 23 3 27 70 88 

185 143 70 3 90 177 2O2 
149 120 48 3 72 147 172 

224 IM 81 S "6 212 226 
IS4 156 66 4 * 190 206 

, Iff] , 

* fS 3 3 


3 3 3 LHJ 3 3 

* JtJJ 3 

FIG. 6. Distribution of sound pressure in a six-foot cubical chamber 
excited by a tone of 162 cps. generated by a cone type loud speaker located 
in one corner of the chamber. The chamber is vibrating in the gravest 
mode involving all three dimensions. At top left is the distribution over 
a plane one foot from one end of the chamber; top center is the plane two 
feet from this end, etc. 

The writer and two of his students, R. Neil and C. Hendrickson, have 
investigated the intensity distribution of sound in a six-foot cubical 
chamber at frequencies corresponding to several of the lowest eigen- 
tones. For the gravest mode of vibration involving all three dimen- 
sions, that is for p = q = r = I, in which case the frequency n is 162 
cps. for the six-foot cubical chamber, the alternating pressure in the 
sound-field is a maximum at (or very near) the boundaries of the 
chamber and diminishes to zero (nearly) at the three planes that 
divide the chamber into eight equal cubes. Fig. 6 exhibits the pres- 
sure distribution over a series of six planes parallel to one wall of the 


chamber, and spaced one foot apart. Over the entire plane midway 
between two opposite walls the pressure was practically reduced to 
zero. For higher modes of vibration the sound-field will be more 
complex, but each mode will be characterized by a definite geometrical 
pattern of nodal and antinodal surfaces. 

These resonance phenomena have more than academic interest; 
they exist in all rooms and are responsible for many of the difficulties 
that attend the placement of microphones in recording and broadcast- 
ing studios. They are likely to be most troublesome in small, rever- 
berant studios, and especially for low-pitched tones. For high- 
pitched tones, that is, tones that have a short wavelength in compari- 
son with the dimensions of the room, several contiguous eigentones 
will be excited, and the overlapping patterns in the room will tend to 
give a diffuse distribution of sound. 

The acoustical engineer must gain a better knowledge of resonance 
in rooms before he can understand and control the complicated phe- 
nomena of intensity distribution and reverberation which are so inti- 
mately related to room resonance. 


In conclusion, the writer wishes to direct attention to a field of re- 
search where science and art meet upon common and fertile ground. 
Acoustics and music have enjoyed a long and intimate relationship, 
although in recent years there has been a paucity of scientific workers 
in the fields of both music and acoustics. Acoustics owes its origin to 
the scientific study of music ; and acoustics is now in a position to re- 
pay its debt to music. The motion picture and radio arts are in a 
particularly favorable position to renew the development of music by 
means of the applications of modern acoustics and, the writer be- 
lieves, much to the advantage of music as well as the motion picture 
and radio arts. 

Already the Bell Telephone Laboratories have developed the so- 
called three-channel amplifying system, by means of which it is pos- 
sible to preserve "auditory perspective" in the reproduced sound, or to 
augment or diminish, at the will of the conductor, the loudness of the 
sound coming from an entire orchestra, or from one or more sections of 
the orchestra, and thus vary the apparent size and composition of an 
orchestra of seventy-five persons as effectively as if there were two 
thousand persons in the orchestra. Harvey Fletcher in collaboration 
with Leopold Stokowski and the Philadelphia Orchestra already have 

244 V. O. KNUDSEN [j. s. M. P. E. 

given several demonstrations of new developments in music made 
possible by this three-channel system. By employing more than 
three channels, and associating low-pass, band-pass, or high-pass 
filters with each channel, even greater versatility is made possible; 
for example, any solo instrument or group of instruments in an orches- 
tra (or in any other musical ensemble) can be amplified any desired 
amount, and the tonal quality of the instruments associated with each 
channel can be altered by suppressing or augmenting the low-, 
medium-, or high-frequency components. Studios with variable and 
controllable reverberation characteristics, or studios associated with a 
reverberation chamber, can be used to produce musical effects that 
would enhance the beauty and interest in many broadcasts or sound 
recordings. These are only a few of the devices the radio and motion 
picture arts may utilize in creating new musical experiences. Here is a 
virgin field where the musician and acoustician, working together, 
can make some noteworthy contributions to the radio and motion 
picture arts. 

Existing musical instruments are limited with regard to pitch and 
loudness ranges, and especially with regard to tonal quality. Our 
conventional musical instruments are capable of producing only a 
small fraction of the almost infinitely many tonal qualities that are 
possible. Electroacoustical instruments can be designed that are 
capable not only of producing, but also of greatly extending, all the 
frequencies, intensities, and tonal qualities of existing musical instru- 
ments. Our present instruments began with varied arrangements 
of bamboo, reeds, grass, tree stumps, skins, stones, plant and animal 
fibers, gourds, wood, and metal and, of course, the finest skills and 
crafts of which man was capable. From these came the Boehm flute, 
the Stradivarius violin, and the most elaborate of all instruments, the 
pipe organ. The flute is, at least in respect of acoustics and me- 
chanics, the most nearly perfected of these instruments, but it is limited 
in its pitch range. The best violins, even when they are in tune, are 
beset with unavoidable "wolf tones." Even our finest organs suffer 
from the adventitious noise of rushing air and clanging action, and the 
shorter pipes produce inharmonic as well as harmonic overtones. We 
have been confined to the best that could 'be obtained from these per- 
fected, but yet imperfect, instruments. Is there any reason to suppose 
that the restricted ranges of pitch, loudness, and quality that these in- 
struments supply are the most beautiful or expressive ones possible ? 
Infinitely many varieties of tone-quality we have never sensed, and 


new extensions of the ranges of both pitch and loudness, are now pos- 
sible by means of electroacoustical instruments. These instruments, 
even if they should prove to be too expensive for personal ownership, 
would contribute new life and interest to motion pictures, radio 
broadcasting, and phonograph recordings. As composers became 
familiar with the possibilities of such instruments they would be able 
to create a new music which would be limited only by the im- 
agination and creative ability of the composer. Research and devel- 
opment are required to produce these instruments, but already several 
electroacoustical instruments have been developed far enough to 
indicate clearly the potentialities of such instruments. 

The music of these new instruments, and all music of the future, 
should be based not only upon the infinitely many tonal qualities 
made possible by synthetic tones, but also upon the physical charac- 
teristics of hearing, such as the dependence of auditory acuity upon 
frequency ; the sensitivity of the ear to differences of intensity and fre- 
quency; the masking effects of certain tones upon other tones; the 
effects of auditory fatigue; the auditory reactions to contrapuntal 
rhythms and melodies ; and the complicated relationships between the 
subjective properties of pitch, loudness, and quality, and the objective 
properties upon which they depend, namely, frequency, intensity, and 
overtone structure. These are only a few of the physical character- 
istics of hearing that should be regarded in creating the music and 
musical instruments of the future. The musician, the psychologist, 
and the esthetician are familiar with many other characteristics that 
could and should guide future developments in music. 

If the recently discovered characteristics of music and hearing had 
been known to Helmholtz, and if the modern instruments of electro- 
acoustics had been available in his time, music probably would have 
gained much more than it did from his brilliant and comprehensive 
studies of the physical nature of music. But we should not despair 
that he left something useful for us to do. The time is now ripe for 
repeating and extending these studies in a modernly equipped labora- 
tory. Thus may we contribute to the raw materials from which there 
will surely emerge a new and superior musical art, free from the imper- 
fections inherent in existing musical instruments, and enhanced 
with finer and more logical pitch and intensity gradations, more and 
better tonal qualities, and more pleasing harmonies, rhythms, and 
forms than man has yet experienced. Here, indeed, is a field where 
the musician, the psychologist, the esthetician, and the acoustician 

246 V. O. KNUDSEN [j. s. M. P. E 

meet upon the same ground; where their joint efforts may lead to 
new and glorious vistas in music; where acoustics, returning to its 
exalted companionship with music, which called it into existence at 
least twenty-five hundred years ago, may make its greatest contri- 
bution to culture. 


1 MEYER, E.: J. Acoust, Soc. Amer., 8 (Mar., 1937), No. 3, p. 155. 

2 Gesundheits-Ingenieur, Bd. 57, S. 556 (1934). 

3 Technical Physics of the U. S. S. R., 3 (1936), p. 1. 

4 Preussichen Akad. d. Wissenschaften, Phys.-Math. Klasse (1936), No. 2. 

5 KNUDSEN, V. O. : "Resonance in Small Rooms," J. Acoust. Soc. Amer., IV 
(July, 1932), No. 1, p. 20. 


MR. KELLOGG: How much of a departure from a plain rectangular room do 
you have to get before you break up the eigentones? 

MR. KNUDSEN: I do not believe we can get rid of the eigentones in chambers 
by means of non-parallel walls. Wherever boundary conditions are imposed 
certain eigentones result. Of course, in the case of the rectangular chamber of 
the type I discussed here where we had a cube, we would not get rid of the eigen- 
tones simply by tilting the walls. There still would be eigentones, although 
they would be much more difficult to compute. 

MR. KELLOGG: Is the eigentone less pronounced with the oblong chamber? 

MR. KNUDSEN: Yes, to a certain extent. When two dimensions are alike, 
you get two eigentones that superimpose, so that certain eigentones are of greater 
intensity. Eigentones depend not only upon the position of the source, but also 
upon the directional characteristics of the source. In ordinary rooms and at 
ordinary frequencies you excite not one eigentone, but usually ten, fifteen, or 
even one hundred in some instances. At high frequencies, many eigen- 
tones overlap, giving an even distribution of sound. At low frequencies and in 
small rooms, we have to take into account the intensity distribution owing to 
the eigentones; there is a definite distribution for each position and each 
orientation of the source. 

MR. HAWKINS: In the cubical room there would be set up one fundamental 
eigentone many times the amplitude of the others, and probably most of the 
others would be harmonics of that lowest one. What would be the difficulty in 
damping the fundamental and the harmonics? 

MR. KNUDSEN: Of course harmonics are present, but there are about ten 
times as many others that are inharmonic. There are as many as thirty 
eigentones per octave, and in many instances, some of the higher harmonics and 
many of the inharmonic overtones would be excited. At the higher fre- 
quencies they taper off quite rapidly, and the extent to which they do so is 
governed by the damping of the room. If a room is very reverberant, a single 
eigentone may be excited almost to the exclusion of -all others, especially at 
low frequencies. If there is considerable damping in the room one single tone 
excites a broader band of eigentones. 


MR. WOLF: The ability to get uniform response or uniform reverberation 
has concerned us for a long time, and we have endeavored to determine whether 
or not we wanted uniform reverberation both in the studio and the theater. Have 
you any thoughts on what kind of characteristic is best for both the studio and 
the theater? 

MR. KNUDSEN: I have no new data. Two years ago, when I spoke to this 
body, I referred to some experiments by Bekesy of Budapest, which, as far as 
I know, are the most recent quantitative experiments. The experiments were 
conducted in a radio broadcasting studio, for string quartet, solo singing, and 
for piano, and led to a flat characteristic, flatter than in other experiments with 
which I am acquainted. 

MR. SKINNER: Have you ever speculated on what would happen if a room 
were built in the shape of a horn? Would it eliminate any of the reverberation 
and give a sound somewhat like the sound in a horn? It may be difficult to do, 
but from a certain standpoint even a complete auditorium might be built in 
such a fashion, if necessary, and eliminate many of the reverberations. 

MR. KNUDSEN: Undoubtedly it would contribute much to eliminating the 
eigentones and give a more uniform distribution. 

MR. WOLF : Some time ago the principle was followed of letting every element 
of a reproducing system have a flat characteristic, from the recording micro- 
phones to the loud speakers in the theaters. The acoustical element, of course, 
can certainly disturb the principle a great deal, and has. What are your opinions 
on the subject? 

MR. KNUDSEN: If you wish to reproduce speech and music with the same 
loudness at which it was originally produced, then the answer would be, cate- 
gorically, yes; but with respect to what is beautiful, what is desirable, I am not 
sure that we are in a position to answer the question. The reverberation char- 
acteristics are somewhat different from the characteristics of the electroacoustical 
apparatus itself, and if you wish to simulate actual room conditions there may 
be some necessity for having a reverberation characteristic other than a flat one. 

My present recommendation with regard to reverberation in the studios is 
that the reverberation time at 100 cps. be about 40 per cent longer than the re- 
verberation time at 512 cps.; a flat characteristic from 512 to 4096 cps., and 
probably a slightly rising characteristic at higher frequencies to compensate for 
the very high attenuation of sound in the air. We are not ready to answer the 
question completely, or, at least, I do not know just what the ultimate practice 
will be. 


Summary. A survey of the history of monopack or multilayer photographic color 
processes, including the methods of greatest importance at the present time: (a) silver 
dye-bleaching methods and (b) silver dye-coupling methods. Silver dye-coupling 
methods appear to be most promising, and have been successfully applied to monopack 
films according to two distinct principles. 

In one method, color-forming compounds are added to the developing solutions. 
Color separation in this method depends upon control of the speed at which bleaching 
solutions penetrate superposed emulsion layers. In the second method, employed in 
the new Agfacolor process, the different color-forming substances, instead of being 
added to the developing solution, are incorporated in emulsions coated in superposition 
so that three differently colored images are simultaneously formed in a single develop- 
ment. The metallic silver is subsequently removed by solvents leaving only pure dye. 

The process is based upon the pioneer work on color-forming methods of R. Fischer 
who, before the World War, developed the process substantially as it is now being used. 
The contributions to improving this process are the perfection of dyestuff -coupling 
components better than those available to Fischer, improved methods of preventing 
diffusion of the color-forming compounds, and methods of precisely controlling the 
manufacture of multilayer film upon a large scale. 

For many years before the time of Daguerre, users of the camera 
obscura were familiar with the colored image thrown upon a focusing 
screen. It is little wonder that with the advent of photography at- 
tempts were made to record these colored images in the same manner, 
and as simply as black-and-white photographs were made. 

The evolution of the art, if we may so refer to it, has been slow 
mainly because of the widely different methods by which the problem 
has been attacked. It was soon discovered that the possibility of 
finding a simple direct-color method was rather remote. This influ- 
enced the trend of research toward more indirect methods of color re- 
production. There, as before, no single path seemed to lead to the 
objective. Many ways of reproducing color sprang up and flourished 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
June 24, 1937. 

** Agfa Ansco Laboratories, Binghamton, N. Y. 



for a time, until in some cases insurmountable obstacles would ap- 
pear, and indeed in most cases they did appear, and finally these ideas 
became history. So great is the stimulation of interest in color photog- 
raphy at this time, and so many very complete bibliographies of 
color photography have been published, that it is not necessary to 
discuss more than a very few of the methods that have shown the 
most promise. 

All these methods had one thing in common a color analysis in 
the neutral scale had first to be made. The color had to be analyzed 
by breaking or dividing it into three components, as suggested by the 
theory of Maxwell. 1 Many very interesting and ingenious methods 
of accomplishing this color analysis or separation have been proposed. 

The most common way is to effect a separation by making three 
exposures on panchromatic film through tricolor filters, and preparing 
color positives from these separate negatives by any of the well known 
procedures. This method is in general use today for still photog- 
raphy, but for obvious reasons is unsuitable for exposures in rapid 
succession, as for instance, motion pictures. Similar color separations 
have been effected by the use of tripack and bipack films and plates. 

It has been customary to classify the various color processes into 
two groups those that produce color by subtractive synthesis and 
those that produce color by the additive method. The additive 
methods are unexcelled in their simplicity and faithfulness of color 
reproduction. However, because of the filters necessary for suc- 
cessful operation, certain losses in light intensity result. Notwith- 
standing this handicap, the Lumiere, Agfa, Finlay, and Dufaycolor 
processes, based upon the additive principle, have proved very suc- 
cessful for producing transparencies in color, the color separation 
being effected by the use of a microscopic tricolor screen element 
placed between the recording medium and the image. An ingenious 
method was applied by Keller- Dorian-Berthon, 2 and later made 
available commercially under the names of Kodacolor and Agfacolor, 
whereby the tricolor screen was placed in front of the optical system 
of the camera and projector, and minute lenticular lenses were em- 
bossed upon the back of the film. Technically there is a vast 
difference between the reseau-based films and the lenticular films 
using the optical filter system before the lens, but in some respects 
the lenticular method may be regarded as a species of screen proc- 
ess in which the filter elements are optically formed. Lenticular 
and screen-plate additive methods are of interest because the processes 

250 J. L. FORREST AND F. M. WING [J. s. M. p. E. 

are simple to use, record all colors simultaneously and in exact register, 
and can be processed simply, quickly, and inexpensively. However, 
with both these systems the loss of light intensity is a major problem, 
and, in addition, the production of duplicates has presented consider- 
able difficulties when attempted on a commercial scale. 

The desire for motion pictures in color has been a persistent and an 
earnest one. Before the end of the past century proposals were 
made for methods of producing motion pictures by the additive pro- 
cess with a mechanical filter arrangement in both the camera and pro- 
jector. It is interesting to note that at that time most experimenters 
in the art seemed to give up hope of having a colored film. Efforts 
were concentrated upon supplying the color from colored filters and 
controlling the paths of light through the filters by black-and-white 
film records. In 1897 such a method was proposed by Isensee. 3 Both 
the camera and the projector were equipped with rotating shutters 
divided into three equal sectors holding the usual red, green, and 
blue-violet filters through which successive pictures were exposed 
and projected. Such processes depend upon persistence of vision to 
fuse the successive images into a complete color picture. Numerous 
additive processes belonging to the persistence-of-vision class have 
been proposed and patented, and a few of the latter have been intro- 
duced commercially. The most prominent was the Kinemacolor, 
which flourished for several years before the World War. This was a 
two-color method in which panchromatic film was exposed at twice 
the normal speed behind a color-sector shutter so that alternate frames 
were exposed behind red-orange and blue-green filters. A black- 
and-white positive was printed in the usual manner, and projected 
at double speed through a similar rotating color-filter on the pro- 
jector. The rapid alternation between the red and green impressions, 
which had to be integrated by the eye as the film was projected, led 
to severe eye-strain. This, together with the additional cost for 
film, proved objectionable. Additive persistence-of-vision methods, 
although very old in principle, have appeared in recent years from 
time to time as new workers in the art have striven to improve and to 
put them into practical use, but none of these attempts at revival 
have more than partially overcome the inherent disadvantages. 

While persistence-of-vision methods were achieving a measure of 
prominence, other experimenters were working on other additive 
processes in which component pictures in two or more primary colors 
were simultaneously projected in register upon the screen. 


Of the simultaneous-projection methods, the most prominent was 
the three-color Gaumont process, which was capable of results beyond 
criticism from the standpoint of quality. However, since the process 
required special projection equipment, theater owners were reluctant 
to purchase this equipment, for which an adequate supply of films 
was not assured. This prevented any large measure of commercial 

When it was realized that any process of color cinematography re- 
quiring special projection equipment was seriously limited from a 
commercial standpoint, increased attention was given to methods for 
producing films in which each frame was a complete color picture. 
This led to the acceptance of subtractive methods and a decline of 
interest in additive processes, with the exception of the screen-plate 
and lenticular methods, which have alone survived. 

Subtractive methods using bipack negatives and double-coated 
positive films have become widely known. In some cases the color 
was produced by inorganic toning, dye toning, or a combination of 
both. In some of the three-color processes the third color, usually 
the yellow, was applied by imbibition. 

The well known Technicolor method, which has been widely 
adopted commercially, is an outstanding achievement in a subtractive 
color process. In this process tricolor separation negatives have to 
be made, from which a transparent print in colors is produced using 
the subtractive colors. 

Of the various methods of color photography that have survived 
none is free from limitations that prevent wide and general adoption, 
nor is there any indication of the direction in which further improve- 
ments of a fundamental nature could be made. 

Because they represented the one branch of the art that gave some 
hope of a brilliant future, the multilayer-film methods have finally 
emerged into prominence after a long period of comparative obscur- 
ity. These methods are characterized by the use of a film having 
three differently sensitized emulsion layers coated in superposition 
upon a single support, with screening dyes added to the emulsions, 
or with interposed filter layers of dyed gelatin to assist in proper color 
separation. The principle is clearly that of the familiar tripack, 
which is the simplest form of tricolor separation, but the three emul- 
sions are coated upon one another to form a single integral unit in- 
stead of the three separate films of the tripack. It is this class of 
multilayer process and its history that are of chief concern. 

252 J. L. FORREST AND F. M. WING [J. S. M. P. E. 

The evolution of the multilayer film began well back in the past 
century. 4 In 1899 Selle divided a single sensitized layer into zones 
of color-sensitivity by controlling the penetration of color-sensitizers 
into the layer for various parts of the spectrum. 

Controlled diffusion, though not described by this name, was em- 
ployed by Wolff-Heide 5 in the production of a multilayer color-film 
process in which two layers of different color-sensitivity are provided 
in one single coating. The Wolff-Heide process is a method of color- 
ing images lying at different depths in one emulsion layer after the 
emulsion has been sensitized according to the methods originated by 

One of the first suggestions for a multilayer coating was made 
about 1905 by Schinzel, 6 who suggested a process called Katachromie. 
This was an outgrowth of the tripack principle, but the emulsion 
layers were coated in superposition, each layer being sensitized to re 
cord one of the tricolor components of the spectrum, and the layer it- 
self dyed the complement of its color-sensitivity. The film was proc- 
essed by a decolorizing method that decolorized the dyes in the re- 
gions where metallic silver was formed by the exposure and develop- 
ment. In this way a subtractive color picture could be formed by 
this multilayer film. Although correct in theory, so many difficulties 
presented themselves in applying the method that it never achieved 
commercial acceptance. Further investigations along this line were 
made by Heymer in 1927 in the Agfa laboratories. 

Caspar also proposed three properly sensitized emulsion layers, 
each of which was dyed complementary to the color to which it was 
sensitive. 7 In order that the staining dye would not interfere, by 
absorption, with the radiation that should be used to expose the 
silver halides, Caspar proposed to shift the color-sensitivity of the 
silver halides somewhat from the maximum absorption of the stain- 
ing dye. In this manner he improved the speed of the film. How- 
ever, means have not yet been found to make the combined film, 
which already contained the actual colors, sufficiently fast for short 
exposure such as would be required in the camera. Caspar's process 
has been introduced commercially, but the multilayer film is used 
only for positive prints, and the usual three-color separation negatives 
are required. Thus the silver dye bleaching method has become an 
intermediate step in the transition from the older methods of indirect 
photography to the modern multilayer process. 

Another important development in color photography as it is now 


applied in multilayer films was the work of R. Fischer, 8 and R. Fischer 
and H. Siegrist, 9 along the line of color development; that is, the for- 
mation of colors in the film during its development. This advance 
provided a new bridge between tricolor separations in terms of silver 
and their translation into dye images. Fischer's work grew out of 
early and preliminary discoveries of Homolka, 10 Schinzel, Luther, 11 
Sforza, 12 and others. Fischer applied this principle of color develop- 
ment in a comprehensive manner to tricolor photography, and in 
patents and publications provided a rather complete disclosure, not 
only of the principle of color development, but the application of the 
principle to multilayer films. 

In addition, Fischer early 9 included the use of specific developers 
for this purpose, such as paraphenylenediamine, or its derivatives, 
and many color-coupling components that could be incorporated in 
the sensitive emulsion layers of a multilayer film, and which would 

eniitivt layer with a yellow dye component, 
yellow titter layer 

Green sensitive layer with a rnasenta dye component. 
Red sensitive layer with a cyan dye component. 
Filrn base. 

FIG. 1. Cross-section of the film. 

provide upon development the proper subtractive colors with the 
same developer. 

Out of this long and active history of color photography, punctu- 
ated by many failures and recorded by a great volume of patents and 
publications throughout the world, there have emerged but few 
color processes that have achieved any real measure of commercial 
acceptance. Of these, the Technicolor process has been mentioned. 
Reference should also be made to the Kodachrome film of the East- 
man Kodak Company. This film and process have been previously 
described, in detail. Suffice it to say here briefly that this film is of 
the multilayer type capable of exposure in an ordinary camera, and 
produces three black-and-white color-separation latent images simul- 
taneously. By an ingeniously devised controlled-diffusion develop- 
ing process carried on in the processing laboratory, each of the separa- 
tion images is converted into the proper dye image. 

The new Agfacolor film is a multilayer film, likewise capable of 
simple exposure in an ordinary camera for the simultaneous formation 



[J. S. M. P. E. 

of color-separation images, and is distinguished by the simplified 
method with which it is processed to provide simultaneously the 
color-images of the black-and-white records with one color develop- 

The discovery of more powerful and more selective sensitizing 
dyes; the improvement and perfection of substances for preventing 
diffusion in and between the layers; the advances in the manufacture 
of photographic emulsions and sensitized materials and methods of 
coating them, together with the progress of the industry in the manu- 





FIG. 2. Simultaneous formation of three color 
records upon exposure. 

facture of synthetic organic dyes, have made it possible for the Agfa 
Laboratories to produce such a simplified multilayer film and process. 
The new Agfacolor film (Fig. 1) comprises a single unitary film 
structure consisting of a support or base upon which is coated in thin 
superimposed layers three light-sensitive silver halide emulsions, 
each made particularly sensitive to one of the primary colors. These 
sensitive layers are arranged on the base in the following order: the 
lowermost layer, i.e., next to the base, is sensitized for red light; the 
next or middle layer is sensitized for green light; the top layer is sen- 
sitized for blue light. Separating the sensitized coatings from each 
other are yellow filter layers, the color of which disappears during 

Sept., 1937] 



developing. The sensitive emulsion layers contain no dyestuffs but 
do contain certain clear and colorless dyestuff-coupling components 
which in subsequent treatment of the film produce colors in the 

By exposing such a film to a colored object (Fig. 2) there will 
be recorded simultaneously three separate color records, each sen- 
sitized layer recording the image to which it is color-sensitive. The 
color formation is brought about by the development of the film. 
The particular developing substance in the developer oxidizes in 






FIG. 3. Effects upon development. 

those places where the exposed silver halide in the layer is reduced to 
metallic silver. This oxidized developing substance couples with 
the coupling components incorporated in the emulsion layers, and 
forms in each layer the insoluble sub tractive color in proportion to 
the silver that is reduced. The coupling compounds incorporated 
in the three emulsion layers have such characteristics as to produce a 
color in each layer that is complementary to the color for which the 
layer is sensitized. Therefore, the color formed in the top or blue- 
sensitive layer is yellow; the color formed in the middle or green- 
sensitive layer is magenta ; and the color that is formed in the bottom 
or red-sensitive layer is cyan. The colors formed in the layers re- 

256 J. L. FORREST AND F. M. WING [J. S. M. p. E. 

main in their respective positions and do not spread or diffuse from 
one layer to the next. In addition, the colors are fast and are not 
affected by the action of the processing solutions. In practice the 
film is exposed in an ordinary camera. By this exposure there are 
formed in the three emulsion layers latent images or color-sensation 
recordings in accordance with the color-sensitivity of each layer; i.e., 
the blue of the subject will be recorded in the top layer, the green 
of the subject will be recorded in the middle layer, and the red of the 
subject will be recorded in the bottom layer. The film is now de- 
veloped to form a black-and-white negative. The developer used 
is an ordinary developer that does not form coupling oxidation prod- 
ucts (Fig. 3). This prevents the formation of colors at this stage. 
After exposure to white light, the remaining silver halides are de- 
veloped in a developer of the para-Phenylenediamine type, the oxi- 
dation products of which couple with the dye component in each of 
the layers and form the subtractive colors in proportion to the metal- 
lic silver that is reduced. 

After this development, the film contains in the layers both the 
metallic silver and the dyes. The silver is now bleached out with a 
reducer, leaving alone in the layers the three superimposed pure dye 
images, which give an accurate reproduction of the colors in the 
original subject. The images are highly transparent and exception- 
ally well suited for projection. Because of the absence of silver 
grains, even larger-sized images may be projected than is customary 
with black-and-white film. 

Agfacolor film has been made available in Europe in the 35-mm. 
width for miniature cameras and will be available shortly for 
amateur motion pictures. It is expected that it will be marketed in 
this country. 

The motion picture industry, of course, will be interested in the 
possibilities that this process may offer in the field of 35-mm. motion 
pictures. Definite advances have been made in this direction, with 
every indication pointing to a practical commercial application to 
this wider field. 


1 WALL, E. J. : "History of Three-Color Photography," p. 2. 
* U. S. Patent 992,151. 

3 German Patent 334,776. 

4 WALL, E. J.: "History of Three-Color Photography," p. 162. 
6 Ibid., p. 164. 


Brit. J. Phot., 1905. 

7 Zeitschr. wissensch. Phot., 34, p. 119. 

8 U. S. Patent 1,055,155 (1913). 

9 Photographische Korrespondenz (1914), No. 640, p. 18; No. 644, p. 208. 

10 Ibid. (1907), p. 55. 

11 German Patent 396,485. 

12 Phot. Coul. (1909). 


MR. COOPER: Why is the separating layer between the green-sensitive emul- 
sion and the red-sensitive emulsion dyed yellow? Should it not be dyed reddish? 

MR. FORREST: The lowermost or red-sensitive layer is not green-sensitive. 
Therefore, a reddish filter layer is unnecessary. 

MR. KELLER: Do I understand correctly that the same color developer will 
transform each of the color-separation layers to a different subtractive color? 

MR. FORREST: Yes. The dye components in each layer are different, so that 
one color developer will produce in each of the three layers one of the subtractive 
colors; i.e., a yellow color will be formed in the top layer, a magenta color will be 
formed in the center layer, and a blue-green or cyan color will be formed in the 
lowermost layer. 

MR. TOWNSLEY: Mr. Forrest, what is the effect of overexposure ? 

MR. FORREST: Color-films are naturally more sensitive to the effect of incorrect 
exposure than are black-and-white films. This is not due so much to the de- 
creased latitude of color-films, but rather to the fact that variations in exposure 
disturb the color balance. Incorrect exposure in the black-and-white scale also 
interferes with the tonal reproduction. However, in the black-and-white film 
the tones still remain in the gray scale; whereas in the case of the color-film, vari- 
ous color tones result, and variation in color is much more quickly detected than 
are variations in the neutral scale. Consequently, one has to be much more care- 
ful in the exposure of all types of color-film than with black-and-white. 

MR. CECCARINI: Do the three layers have identical gradation? 

MR. FORREST: It is desirable that they should have for maximum latitude, and 
as nearly as possible they do have the same gradation. However, the three color 
characteristic curves can not be exactly the same. 

MR. OFFENHAUSER: What is the difference in recording sound on Agfacolor 
film with ultraviolet, as against recording with white light? 

MR. FORREST: It is too soon to make a definite statement in regard to sound re- 
cording on Agfacolor film. However, it will be necessary to use light that will 
penetrate the three layers in order to produce a satisfactory sound-track. 



Summary. The photographic recording of sound is accomplished by modulating 
a narrow beam of light and projecting it upon a strip of moving film. There are 
three ways in which the amount of exposing light may be varied. A light-beam of 
fixed dimensions may have its intensity varied; a beam of constant intensity and 
length may have its width varied; or a beam of constant intensity and width may have 
its length varied. The first two types of modulation produce variable-density sound- 
tracks, while the third type produces variable-width tracks. 

The recording optical system can be made to modulate either the intensity or the 
length of the light-beam. The unit consists essentially of an incandescent lamp to 
produce the light, a system of lenses to direct the light, an aperture and slit to limit 
the light, and a reflecting mirror galvanometer to modulate the light. A magnetic 
shutter for ground-noise reduction is also part of the standard variable-width re- 
cording unit. A system of mirrors and lenses intercepts a small portion of the re- 
cording light and projects it upon an external card. This system magnifies the 
deflection of the galvanometer and shutter to such extent that the degree of modulation 
and the zero settings can be observed easily by the unaided eye. 

Many different types of sound-track can be made uith the recording optical system 
without sacrificing any of its advantages as a light modulator. By the use of the 
appropriate condenser and aperture assembly, the system will record standard bi- 
lateral variable-width track, standard variable-density track, push-pull class B 
variable-width track, push-pull class A variable-density track, and push-pull class 
A variable-width track. The manner in which each of these systems functions is 
shown and described in detail. 

The photographic recording of sound is accomplished by modulat- 
ing a narrow beam of light and projecting it upon a strip of moving 
film. There are three ways in which the amount of exposing light 
may be varied. A light- beam of fixed dimensions may have its in- 
tensity varied; a beam of constant intensity and length may have 
its width varied ; or a beam of constant intensity and width may have 
its length varied. The first two types of modulation produce vari- 
able-density sound-tracks, while the third type produces variable- 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
June 15, 1937. 

** RCA Manufacturing Co., Camden, N. J. 




width tracks. 1 It is the object of this paper to describe the RCA 
light-modulating system, to discuss some problems connected with 
its design, and to show how it is adapted to record variable-width and 
variable-density sound-tracks of various types. 

The light-modulator consists essentially of an incandescent lamp 
to produce the light, a system of lenses to direct the light, an aperture 
and slit to limit the light, and a reflecting mirror galvanometer to 
modulate the light. A magnetic shutter for ground-noise reduction 
is also part of the variable-width recording unit. Fig. 1 shows the 
optical layout. The image of the filament A is formed at the galva- 
nometer mirror F by the combination of lenses, B and E, Most of the 

FIG. 1. Optical system for variable- width recording. 

power to form this image is in the condenser B. The intermediate 
lens E has just sufficient power to form an image of the aperture C 
upon the slit H. The condenser G forms an image of the mirror F 
upon the objective lens J. The objective in turn forms an image of 
the slit upon the film K. The filter / serves to restrict the radiant 
energy to a narrow band in the ultraviolet. The two condensers, B 
and G, and the two objectives, E and /, form a relay optical sys- 
tem in which planes of non-uniform illumination appear at the fila- 
ment, the galvanometer mirror, and the last objective, while planes of 
uniform illumination appear at the aperture, the slit, and the film. 
The lens mirror L is located immediately below the slit, and reflects 
a corner of the recording light-beam for monitoring purposes. The 
monitoring beam strikes the mirror N, is reflected vertically through 
the lens to the mirror M, which directs it to the monitoring card P. 

260 G. L. DlMMICK [J. S. M. P. E. 

An image of the galvanometer mirror F is produced at lens by the 
lens mirror L. The lens 0, in turn, forms an image of the plane H 
upon the card. The action of the two monitoring mirrors, M and 
N, is to rotate the planes of vibration through 90 degrees. Vibra- 
tion of the galvanometer mirror in a vertical plane produces horizon- 
tal vibration of the vertical edge of the triangular monitoring beam. 
Horizontal motion of the shutter vanes D results in vertical motion 
of the horizontal edge of the monitoring beam. 

The Recording Lamp. It is known from the laws of optics that if 
we neglect the loss of light by reflection and absorption, the axial 
illumination at the final image produced by any aplanatic system of 
lenses depends only upon the brightness of the source of the solid 
angle of the pencil of light converging to the center of the last image. 
From this we conclude that the efficiency of the recording optical 
system is independent of the size of the light-source, provided the 
brightness of the source and the size of its image upon the galva- 
nometer mirror are kept constant. There are other factors, however, 
that determine the size of the recording lamp. 

The life of an incandescent lamp depends, among other things, upon 
the ratio of the volume to the surface area of the filament. Since the 
volume varies as the square of the wire diameter and the surface area 
varies directly as the diameter, it follows that the lamp life at a given 
temperature increases with the wire diameter. The length of the 
filament wire must be increased together with the diameter in order 
to prevent excessive end-cooling. The coil length must be approxi- 
mately twice the diameter so that the filament image can be made to 
fill the galvanometer mirror in height, allowing the cooler end-turns 
to fall off the mirror. 

Other factors that favor a large light-source are the ease of lamp 
adjustment, stability of the filament in operation, and the simplicity 
of condenser design. If the filament is misaligned in a vertical plane 
by an amount equal to its own diameter, the recording light is re- 
duced to zero. A small-diameter source would require large magni- 
fication, which would make it critical to adjust. Also the effects of 
filament sag and mechanical vibration would be increased. The 
speed required of the first condenser bears an inverse relation to the 
source size. A single-element condenser can be used effectively only 
if its speed does not exceed about f/2. 

All these factors point to the desirability of a large light-source, 
but there are limitations in this direction also. It is advantageous to 

Sept., 1937] RCA RECORDING SYSTEM 261 

keep the power requirements low, especially when the power is ob- 
tained from storage batteries. The problems of lamp current con- 
trol, lamp socket design, and heat dissipation grow very rapidly with 
the size of the lamp. All things considered, the most satisfactory 
light-source has been found in a lamp having a rating of 10 volts, 7.5 
amperes. The filament helix has an outside diameter of 76 mils and 
a length of 175 mils. The coil is slightly curved to improve the uni- 
formity with which the aperture is illuminated and to increase the 

FIG. 2. Curved filament: (a) front view; 
(i) top view. 

illumination obtained from the convex side at the expense of that ob- 
tained from the concave side. The bulb is one inch in diameter and 
is made of glass having a high transmission at 3650 A. Fig. 2 is an 
enlarged photograph of the lighted filament. Fig. 3 shows how the 
illumination varies with the angle for both the curved and the straight 

The Optics. 2 The intermediate lens E and the objective lens /, 
(Fig. 1) are both achromats of the type largely used in microscopes. 
They are so corrected as to bring the ultraviolet line (3650 A) and the 
mercury green line (5461 A) to focus in the same plane. Like most 



[J. S. M. P. E. 

microscope objectives, the correction for spherical aberration is 
nearly perfect, and diffraction alone sets the limit of resolution. The 
objective lens / has a focal length of 16-mm. and a numerical aperture 
of 0.25. Maximum resolution of this lens is attained when the image 
of the galvanometer mirror is about two-thirds the size of the lens 



FIG. 3. Variation of illumination with angle for (a) 
straight filament lamp; (b) curved filament lamp. 

Under this condition, the resolving power is given by the 

Z = 


where Z is the smallest separation of two points, X is the 
wavelength of the light, and N.A. is the full numerical aperture of the 
lens. For a wavelength of 3650 A the objective is capable of resolving 
two points separated by a distance of one thirty-fifth of a mil. It is 
evident from this that no difficulty is experienced in projecting upon 
the film a beam of light having a width of a quarter mil, or one-eighth 
of the length of a wave on the film at 9000 cps. The size of the 
mechanical slit is 1.9 mils by 570 mils, and the reduction ratio of the 
objective is 7.5 to 1. 

Condensers are not usually required to produce good images, but 
their effectiveness in concentrating the light is increased as the aber- 

>Sept., 1937] 



rations are reduced. Although it is not possible to eliminate spherical 
aberration from a simple spherical lens, it may be minimized and 
coma may be eliminated completely by choosing the radii so that the 
deviation of the rays is divided equally between the two surfaces. In 
designing the condensers for the recording optical system the rule of 
equal deviation was adhered to. The lenses were made as thin as 
possible to reduce absorption and the radii were chosen to give the 
required focal length for a wavelength of 3650 A. Bausch & Lomb 

FIG. 4. General construction of RCA photophone magnetic galvanometer. 

spectacle crown glass was used because of its high transmission at 
this wavelength. 

The Recording Galvanometer. The development of a large mirror 
magnetic galvanometer 3 (Fig. 4) presented many problems. One of 
the most interesting of these and the last to submit to solution was 
the problem of damping. The oscillograph galvanometers previously 
used for sound recording obtained their damping from oil surround- 
ing the ribbons and mirror. Although the damping properties of oil 
are excellent, there are several reasons why its use in recording galva- 
nometers is objectionable. The coefficient of damping varies over a 
wide range with temperature. In order to obtain damping, it is neces- 



[J. S. M. P. E. 

sary to move a considerable mass of oil. It is difficult to seal the gal- 
vanometer sufficiently to prevent oil leakage. 

The first dry galvanometers of the magnetic type were damped by 
a pad of rubber surrounding the armature. By loading pure gum 
rubber with tungsten powder, a high power- 
factor, low temperature coefficient, and long 
life were achieved. Although the method 
provided sufficient damping at resonance it 
did not prove successful for other reasons. 
In addition to the required resistance, the 
rubber supplied considerable stiffness and 
mechanical hysteresis. But stiffness added 
in this way is not reliable enough to be de- 
pended upon for armature stability, so that a 
loss of sensitivity resulted. Hysteresis is seri- 
ous because it gives rise to a shifting zero 

The method of damping eventually adopted 
makes use of the desirable properties of tungsten-loaded rubber, but 
does not permit it to influence the low-frequency response of the 
galvanometer. A cross-section taken through the armature and 
damping assembly is shown in Fig. 5. Two small rectangular pieces 
of tungsten-loaded rubber B are cemented to the armature A about 

FIG. 5. Cross- 
section of armature 
and damping assem- 
bly of galvanometer. 


FIG. 6. Electrical equivalent of damping assembly. 

midway of its length. A bronze yoke C straddles the armature 
and presses firmly against the outside faces of both pads. The metal 
yoke does not touch the armature or the modulation coil surrounding 
it. When the armature vibrates at low frequencies the yoke moves 
with it and has no effect at all upon the stiffness. At high frequen- 

Sept., 1937] 



cies, the inertia of the yoke causes it to stand still and the armature 
vibrates inside it, compressing the rubber and damping the peak. 

The electrical equivalent of the mechanical damping system is 
given in Fig. 6. The mass of the armature and mirror is represented 
by Li, while C\ represents the armature compliance. L 2 represents 
the mass of the yoke, Cz the compliance of the rubber, and r 2 the ef- 
fective resistance of the rubber. The resistance and reactance of the 




0.1 1.0 10-0 

FIG. 7. Resistance and reactance of damping assembly. 

damping circuit has been determined from a mathematical analysis 
of the equivalent circuit. Expressed in mechanical terms these are : 

M 2 (l - 

- 1 

and - - = 


X 2 is the reactance of the damping assembly, 5 2 is the stiffness of the 
rubber, Rz the resistance of the damping assembly, u the ratio of the 
frequency in question to the resonance frequency of the damping 
assembly, and B is the bluntness of the damping assembly as a res- 
onator. The bluntness of a tuned mechanical vibrating system is 
the ratio of the amplitude of deflection at low frequencies to the am- 
plitude of deflection at resonance for a constant vibrating force. With 
tungsten-loaded rubber as the damping material, the bluntness of the 
damping assembly is 0.6. By placing this value in the two equations 



[J. S. M. P. E 

above we may determine the relations between resistance, reactance, 
and frequency. The curves in Fig. 7 show this relation. Values of 
Xz/Si that are negative indicate mass reactance, while the positive 
values indicate stiffness reactance. 

The effect of the damping assembly upon the galvanometer charac- 
teristic is shown in Fig. 8. The peak is reduced from 12 db. to about 
3 db. The droop that occurs immediately before the peak is caused 
by the inductance of the modulation winding. This can be overcome 
and the frequency characteristic improved by placing a condenser 

FIG. 8. Effect of damping upon galvanometer response: (broken curve) 
damped; (solid curve) undamped. 

across the biasing winding to neutralize the inductive reactance. 
Its value may be chosen properly to boost the response where the 
curve is lowest and to reduce the response at the peak. The effect 
of bias capacitor upon galvanometer response is shown in Fig. 9. 
The damping assembly is in place and constant voltage is applied to 
the grid of the last tube. The effect of the bias capacitor upon the 
impedance of the modulation winding is shown in Fig. 10. 

Variable-Width Recording. The vibrating-mirror system of light- 
modulation is endowed with a high degree of flexibility. This flexi- 
bility is made possible by the fact that the galvanometer does not 
itself modulate the light, but rather imparts angular vibration to a 
beam, the size and shape of which is determined by a stationary aper- 

Sept., 1937] 



ture. The intersection of the vibrating beam with a narrow slit de- 
termines the extent and form of the modulation. As shown in Fig. 
11, variable- width sound-tracks may be produced either by making 
the aperture rectangular in shape and vibrating its image across the 
slit lengthwise, or by providing the aperture with one or more sloping 
edges and vibrating its image at right angles to the slit length. The 
second method is preferred because it enables us to record many types 
of track that would otherwise be extremely difficult if not impossible. 
If the aperture has more than one sloping edge or if the value of the 
slope is less than unity, the sensitivity of the modulator is increased 

FIG. 9. Effect of bias condenser upon galvanometer response : (broken 
curve) no bias condenser; (solid curve) 0.035 /^f across biasing winding. 

in direct proportion to the number of sloping edges and in inverse 
proportion to the value of the slope. In case the objective is not 
filled with an image of the galvanometer mirror, the advantage 
of multiple sloping edges may be utilized to increase the illumination 
of the recording beam instead of increasing the sensitivity. This is 
accomplished by moving the mechanical slit and associated condenser 
closer to the galvanometer. If the sensitivity of the modulator is 
kept constant, the illumination at the film is directly proportional to 
the square of the number of sloping edges and inversely proportional 
to the square of the slope. 



[J. S. M. P. E. 

Fig. 12 shows three types of variable- width sound-track together 
with the form of aperture required for each. They are (a) the standard 
bilateral track, (b} the class B push-pull track, and (c) the class A push- 


10. Effect of bias condenser upon galvanometer impedance : (broken 
no bias condenser; (solid curve) 0.035 rf across biasing winding. 

pull track. Many other types such as the unilateral and multilateral 
tracks are easily obtained. The black rectangles represent the 
shutter vanes that mask the unused portion of the light-beam for 
noise-reduction. The class B track requires no noise-reduction, 
but inherently possesses a higher signal-to-noise ratio than any other 



FIG. 11. Two methods of making variable- width sound records. 

known system of film recording. At the present time, the class B 
track is not suitable for general theater release, because of the neces- 
sity of maintaining an accurate sensitivity -balance in the push-pull 
reproducer. The class A push-pull track does not require that the 

Sept., 1937] 



reproducer be accurately balanced, and the recording is no more diffi- 
cult to handle than for standard track. In converting a recording 
optical system from standard to class A push-pull, it is necessary 
only to change apertures, the same shutter being used in both cases. 
If it is desired, however, the speed of the shutter operation may be 
increased, since modulation of the light-beam by the two vanes is in 
phase and is largely cancelled in the push-pull transformer. High 
frequencies reproduced from the variable-width push-pull class A 



FIG. 12. 

Three types of variable-width sound-track: (a) Standard bi- 
lateral; (b) Class B push-pull; (c) Class A push-pull. 

track are exceptionally clean even though the print and negative 
densities vary somewhat from the values recommended for standard 
track. This is true because even-harmonic distortion and distortion 
due to audible variations in average transmission are not reproduced. 
Variable-Density Recording. The advantages of the light-modu- 
lator are by no means limited to variable-width recording. Linear 
variable-intensity modulation of a quarter-mil light-beam may be had 
without reducing the optical efficiency or sacrificing the advantage of 
visual monitoring. The method of converting from angular-mirror 
vibrations to light-intensity variations is shown in Fig. 13. A rec- 
tangular beam of light is focused upon the slit in such a manner that 



[J. S. M. P. E. 

three of its edges are sharply defined, while the fourth edge (parallel 
to the slit) is given a linear gradation in intensity. 4 The beam is 
vibrated at right angles to the slit, causing the transmitted light to 
vary with the position of the rectangle. Fig. 14 shows how a linear 

gradation or penumbra may be 
formed. Light from a source F, of 
uniform brightness, is observed 
from the three positions A, B, and 
C. The straight edge of an opaque 
aperture is on a line between the 
center of the source and point B. 
It is evident that from point A 
none of the filament can be seen, 
from point B half the filament is 
visible, and from C all of it is 
visible. The gradation of light in- 
tensity from A to C is therefore 

Fig. 15 shows how this principle 
is applied to the recording optical 
system. The only changes in the optical layout are the addition of 
the penumbra aperture T and the cylindrical lens N, and the elimina- 
tion of the ultraviolet filter /. The aperture C is rectangular in shape 
and is focused upon the slit as before. Part of the light passing one 
of its edges is intercepted by the aperture T, forming a penumbra at 

FIG. 13. Penumbra light-beam 
and slit for standard variable-density 

_ --A 

FIG. 14. Formation of linear penumbra. 

the slit like that shown in Fig. 13. It makes no difference in the 
final result whether the penumbra aperture is placed between the 
lamp and rectangular aperture or between the rectangular aperture 
and the intermediate lens. It is of practical importance, however, 
to place it inside the closed condenser barrel where it may be kept 
clean. The purpose of the cylindrical lens N is to produce a slight 

Sept., 1937] 



magnification of the filament image in a vertical plane and allow this 
image more than completely to fill the galvanometer mirror. In 

FIG. 15. Modified optical system for standard variable-density recording. 

this way any irregularities of the upper and lower edges of the filament 
coil are cut off and do not effect the linearity of the light gradation 
at the slit. The height of the penumbra is determined by the height 

FIG. 16. 


(a) Penumbra masks for class A push-pull variable-density re- 
cording; (b) apposed penumbras at the slit. 

of the mirror and the distance between the two apertures T and C. 
This height is so adjusted as to require approximately the same gal- 
vanometer deflection for 100 per cent modulation of both variable- 
width and variable-density tracks. 



[J. S. M. P. E. 

Ground-noise reduction for the standard variable-density track 
is accomplished by biasing the galvanometer. The noise-reduction 
amplifier used to operate the variable-width shutter system performs 
equally well for variable-density. When there is no modulation, 
the penumbra is shifted so that the slit is nearest the dark side. 

Class A push-pull variable-density tracks are also possible with 
very little change in the optical system. Fig. 16 shows the required 
penumbra aperture and the appearance of the light-beam at the slit. 
The two adjacent penumbras face in opposite directions so that as 
the whole light-beam is vibrated across the slit the quantity of light 

FIG. 17. Modified optical system for push-pull variable-density recording. 

passing through one half is increasing while that passing through the 
other half is decreasing. 

The layout of the optical system for class A push-pull variable- 
density is shown in Fig. 17. Cylindrical lens V is used in combination 
with the intermediate spherical lens E. In the vertical plane the 
spherical lens forms an image of the rectangular aperture C upon the 
slit. In the horizontal plane the combination of the cylindrical and 
spherical lenses forms an image of the penumbra masks upon the 
slit. The cylindrical lens next to the lamp is not required here as it 
was for the standard variable-density system. The cylindrical lens 
V tends to shorten the length of the filament image. When this is 
overcome by increasing the magnification of condenser B, the height 
of the image more than fills the mirror, as desired. 

Noise-reduction may be effected by making the two penumbra 
masks the vanes of a double-vane shutter similar to the shutter em- 

Sept., 1937] RCA RECORDING SYSTEM 273 

ployed for standard and push-pull variable-width recording. When 
the modulation is low the current operating the shutter increases, 
pulling the penumbra masks apart and shifting the penumbras in op- 
posite directions so that the illumination of both halves of the track 
is reduced. 

Acknowledgment of important work that has contributed to the 
development of the above-described light-modulating system is due 
Messrs. A. C. Hardy, E. W. Kellogg, C. R. Hanna, L. T. Sachtleben, 
H. J. Hasbrouck, J. O. Baker, and C. N. Batsel. 


1 MACKENZIE, D.: "Sound Recording with the Light-Valve," /. Soc. Mot. 
Pict. Eng., XH (Sept., 1928), No. 35, p. 730. 

2 HARDY, A. C. : "The Optics of Sound Recording Systems," J. Soc. Mot. Pict. 
Eng., XII (Sept., 1928), No. 35, p. 760. 

3 DIMMICK, G. L. : "Galvanometers for Variable-Area Recording," /. Soc. 
Mot. Pict. Eng., XV (Oct., 1930), No. 4, p. 428. 

4 SACHTLEBEN, L. T. : "Characteristics of Photophone Light-Modulating 
System," /. Soc. Mot. Pict. Eng., XXV (Aug., 1935), No. 2, p. 175. 


MR. SKINNER: Push-pull recording seems to have the advantage of cancelling 
the ground-noise, yet in all cases you have two different systems and still add 
shutters to reduce the noise. Is it possible, theoretically, to cancel the noise 
without shutters? 

MR. DIMMICK: The Class A push-pull method does not reduce ground-noise 
any more than the standard types of tracks. The standard push-pull B does, 
by virtue of the fact there is no modulation and the track is almost completely 
black. In the Class A push-pull system it is necessary, as well as with the stand- 
ard tracks, to use the shutter system for noise-reduction, but the push-pull 
arrangement considerably improves the response at high frequencies, eliminates 
the distortion that might otherwise exist at those frequencies, and eliminates 
any shutter noise that may occur due to the movement of the shutter lens. 

MR. SKINNER: It seems to me that there is some sort of cancellation, at least 
of ground-noise. 

MR. DIMMICK: As far as I know the variations produced by the ground-noise 
are not cancelled in a push-pull transformer, since they are random variations. 



Summary. The possibility of reproducing sound directly from the negative record 
offers an improvement in sound quality because it avoids the deterioration of defini- 
tion, wave-shape, and volume range caused by the printing process. 

In order to eliminate the distortion inherent in variable-density sound negatives, 
the playback amplifier must produce the same type of compensating distortion that 
occurs in good straight-line prints. The theoretical circuit requirements for an 
amplifier of this type are derived, and the RA-222 negative playback amplifier de- 
veloped by the ERPI engineering department, in accordance -with these requirements, is 
described. In addition to the basic distortion circuit, the RA-222 amplifier satis- 
fies practical requirements, such as self-contained power supply and adjustments 
for negative gamma, amplitude, and frequency characteristic. 

Experiences in various fields of use are reported, such as sensitometric measure- 
ments, print control, re-recording, and high-quality reproduction. 

In the production of sound recordings on film, two photographic 
steps are involved. First, one obtains a negative sound record by 
direct exposure to light modulated by the sound signals. In the sec- 
ond step, a positive record is obtained by a printing process. It is 
inevitable that the second photographic step introduces quality losses. 
These losses are of a double nature : the sharpness of the signal image 
is diffused, and thereby high-frequency losses and distortions are 
introduced; and the graininess of the positive emulsion increases the 
background noise level. A better sound quality can therefore be 
expected if it is possible to eliminate the printing operation. 

Successful attempts have been made to obtain negatives that can 
be reproduced directly. In variable-density recording these are 
known as "toe" negatives. Anybody who has heard reproduction 
of good toe negatives admits the great clarity and firmness of tone 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received May 
19, 1937. 

** Electrical Research Products, Inc., New York, N. Y, 



shown by these films. Toe records, however, are subject to several 
limitations. They can not be commercially produced in sufficient 
quantity for theater release. Furthermore, the curvature of the 
toe characteristic introduces harmonic distortion unless the modula- 
tion is held fairly low, and thus their noise level is as high as or higher 
than that of prints. 

In some special fields, such as in editing newsreels, so-called 
straight-line negatives have been reproduced without printing. The 
sound from these negatives is, of course, badly distorted by the curva- 
ture of the negative characteristic, but listeners were invariably im- 
pressed by the low noise-levels of these negatives, which is due to the 
finer grain of films developed to a low gamma. 

Based upon these advantages of sound negatives, the Engineering 
Department of Electrical Research Products, Inc., set itself the task 
of providing electrical means by which a straight-line negative could 
be reproduced free from distortion. These electrical means must 
produce a compensating amplitude distortion equivalent to that which 
occurs in an ideal photographic printing process. Since the planned 
device must be capable of reproducing negatives that were de- 
veloped to different degrees of contrast, it must contain a control 
that permits an adjustment of the "apparatus gamma." The gamma 
adjustment had to be independent of the signal frequency, and could 
therefore contain only resistive elements, such as a rheostat or gain 
control. This requirement practically determined the design of the 
entire device, as will be shown by the following mathematical reason- 

If 6i is the instantaneous input voltage and e the output voltage, 
the analogy of a straight-line printing process requires that 

e = Cei-r (1) 

Now, at the gamma control point the signal voltage e c is an un- 
known function of the input voltage and of the output voltage 

e e =f(ei-r) (2) 

The control feature requires that an amplitude change of e c pro- 
duces a gamma change in the over-all characteristic; therefore 

/(*-') =/(*-* r ) (3) 

The only function that satisfies equation 3 is the logarithm. It 
is therefore necessary that the voltage change at the control point be 
proportional to the logarithm of the output. Incidentally, due to 

276 W. J. ALBERSHEIM [J. S. M. P. E. 

equation 1, it is also proportional to the logarithm of the input volt- 
age, as expressed by equation 4; 

e c = k log e = kr log 0, (4) 

In order to transform this logarithmically distorted signal into the 
desired linear characteristic, it has to be subjected to an exponential 
amplitude distortion as shown in equation 5; 


This type of distortion is easy to achieve, because amplifying tubes 
with exponential characteristics were developed years ago for the 
purpose of volume control. There remains the task of providing a 
logarithmic volume distortion for the "volume control stage." No 
tubes with logarithmic characteristics are available. However, if 
one impresses a linear characteristic upon the anode of an exponential 
tube, then its control grid will perforce follow the inverse function of 
the exponential tube characteristic, which is the desired logarithmic 
function. In the device here described the linear response of the 
plate was obtained by reverse feedback. Fig. 1 shows schematically 
the circuit diagram of the RA-222 negative playback amplifier de- 
veloped by the Engineering Department. The first tube shown at 
the left is a high-mu, straight-line amplifier tube. Its output volt- 
age is coupled to the grid of the second tube, which is an exponential 
type of amplifying tube, and the space-current of the second tube is 
fed back into the grid circuit of the first tube. Thus, over a wide 
range of input voltage the grid-swing of the second tube is propor- 
tional to the logarithm of the input voltage. This reverse feedback 
has the additional desirable effect of stabilizing the input tube and of 
reducing its internal distortion as well as its effective input imped- 
ance. Thus it becomes possible to connect the attachment to the 
photocell terminals of existing apparatus through a low-capacity 
cable of reasonable length without undue loss at high frequencies. 
This is doubly important because the input voltage is proportional 
to the distorted transmission of a straight-line negative. If its 
harmonics are suppressedi they appear as inverted harmonics in the 
output of the negative playback amplifier. 

It is difficult to utilize the logarithmic grid voltage of the second 
tube directly for control purposes because if power is drawn from this 
high-impedance circuit the logarithmic amplitude is distorted. This 
logarithmic grid voltage is, therefore, impressed directly upon the 
grid of an auxiliary straight-line amplifier tube, tube No. 3. This 



tube serves a double purpose. It isolates the control circuit from 
the logarithmic feedback circuit, and provides gain and power for 
control purposes. In addition, it reverses the polarity of the loga- 
rithmic signal as required by equation 4. That such a reversal is 
necessary becomes evident from the consideration that in the photo- 
graphic printing process, as well, the optical transmission of the record 
changes inversely as the illumination. 

The output voltage of the third tube is adjusted in amplitude by the 
gamma control, shown in the schematic diagram as RU, and impressed 
upon the grid of the exponential output tube TV 

This completes the list of basic circuit elements. Actually there 

FIG. 1. Schematic diagram of playback amplifier. 

are, of course, a number of additional practical requirements: The 
amplifier must be capable of reproducing not only the signal fre- 
quencies but also the d-c. components caused by even harmonics and 
by noise-reduction bias. Therefore, the entire structure from the 
grid of the input tube to the anode of the output tube is a straight 
d-c. amplifier containing only resistive elements. In view of the 
high gain in the first stage it is necessary to compensate for the varia- 
tions in the space-current of individual tubes by providing the rheo- 
stat Ri 6 . A similar precaution is taken in the screen-grid circuit of the 
third tube by providing a potentiometer PI. Finally, the initial 
value of the gamma control Rn is connected to an auxiliary rheostat 
RIZ in order to fit the calibration of the gamma control to the exponen- 
tial gain characteristic of the output tubes. 

Further problems were introduced by the fact that the exponential 

278 W. J. ALBERSHEIM [J. S. M. p. E. 

tubes contain not only exponentially acting control grids but also 
screen-grids of a more nearly linear characteristic; and finally, the 
entire unit was to be operated from a single power-supply which in- 
troduced an inter-coupling of all the tube elements through the various 
bleeder resistances. It was found necessary to introduce compensat- 
ing or "neutralizing" resistance connections at various points in order 
to offset amplitude distortions that might otherwise have been caused 
by this inter-coupling. 

The remainder of the circuit elements are of an auxiliary nature 
for convenience of operation. An output transformer was connected 
to the plate circuit of the output tube in order to match the normal 
500-ohm or 200-ohm system amplifier inputs. At this point a trans- 
former is permissible because the harmonic distortions have been 
eliminated and the d-c. components are no longer essential. The 
output circuit is also equipped with a low-frequency equalizer and an 
attenuator in order to transmit to the system amplifiers a level and a 
frequency characteristic similar to those of a normal photoelectric 
cell amplifier. In addition, the equipment provides a switching ar- 
rangement that makes it possible to change over from negative play- 
back to a straight photoelectric cell amplifier circuit for print repro- 
duction. This is accomplished by connecting the linear space-cur- 
rent of the second tube into the output circuit. 

A group of push-button keys makes it possible to measure the plate 
currents of all the tubes on a single milliammeter MI. 

The locations of the various controls are visible in Fig. 2, which is 
a photograph of the assembled negative playback amplifier with its 
power unit. 

In tuning up, the operator first allows the apparatus to warm up 
for a few minutes. Next, the coupling resistor R 16 is adjusted for 
the correct plate current of the second tube. Third, a direct current 
of 0.15 milliampere is impressed upon the anode input. This can be 
done by connecting the positive terminal of a 1.5- volt dry cell to 
ground and the negative terminal through a series resistance of 9 
megohms to the anode terminal. With this input, P t is adjusted 
until the plate current of the fourth tube equals about 1 milliampere 
regardless of the gamma control setting. Finally, the gamma con- 
trol is adapted to a negative gamma of 0.5, and the gamma vernier 
R, 2 is adjusted until the apparatus gamma equals two divided by the 
ratio of specular to diffuse gamma, that is, about 1.5. 

The apparatus gamma can be measured either with direct current, 



by plotting input versus output currents on a log scale, or with a com- 
bination of direct and superimposed alternating current by noting 
the output attenuation that compensates for a given input attenua- 
tion. Once these adjustments are made, they remain unchanged 
until one of the tubes becomes exhausted and has to be exchanged; 
that is, for several months at a time. 

FIG. 2. 

Negative playback amplifier with 
power unit. 

The apparatus here described has been tried out over a considerable 
period of time, and the following uses have been made of it : 

(2) Newsreel records were judged and edited from negatives. 

(2) Sensitometric measurements were made by finding minimum distortion 
of single-frequency test-films and " Adb." tester. 

(3) Prints of unsatisfactory quality were checked by comparing them with 
the quality of the original negative. In some cases it could be shown that the 
negative had been developed to an unusual gamma by observing the setting of 
the gamma control at which the best sound quality was obtained from the nega- 

(4) Feature films were re-recorded directly from the original negative, thus 
avoiding the quality losses in the printing process. 


(5) For special showings the negatives were played in synchronism with posi- 
tive pictures by means of a double-film reproducing attachment. 

Experience has shown that the equipment is especially suited for 
the reproduction of noise-reduction negatives. The "hush-hush" is 
greatly reduced because the unbiased noise-level is lower. Never- 
theless, the effective amount of noise-reduction is greater in the nega- 
tive than in the print, because in the print, low-level signals corre- 
spond to darkened film having decreased volume range; whereas in 
the negative, low-level passages increase the transmission and the 
volume range of the film. 

Since the negative playback amplifier produces reciprocal amplitude 
distortion, a decrease in lamp current increases the output signal, and 
vice versa. For this reason, clear film should be used as leader when 
reproducing negatives, and splices should be punched out just as 
they are in preparation for the printing process. 


G. M. BEST** 

Summary. The sound-track cutter requires a film reproducer in his daily routine 
work: a reproducer that can be threaded quickly and will not tear or damage the film, 
and will produce sound quality of sufficient excellence to judge splits or cut-outs in 
music recording. 

Such a device has recently been developed, and its mechanical details and operation 
are described. By means of a geared motor drive and a series of friction rollers, the 
sound-track is fed past the light-beam of the reproducing system at standard speed, 
with a reversible feature that is automatic and instantaneous. No sprockets or clamp 
rollers are used, and the work of the cutter is speeded materially through its use. 

In most studios the dubbing room staff includes a number of sound- 
track cutters and assistants who prepare the speech, music, and sound 
effects for the dubbing mixers. Each cutter is provided with a room 
equipped with the conventional moviola and track units, which can 
be coupled together or run separately, as desired. 

In assembling the various tracks, frequent use of the track repro- 
ducer alone is required, and when a number of tracks are to be assem- 
bled in a hurry, the operation is slowed down by the necessity of 
threading the film through the reproducer, which may not always be 
in a convenient position on the cutting table. In addition, the ma- 
chine must be started, stopped, and reversed with hand switches, 
and a wrong move frequently results in torn film, requiring reprints 
and consequent delays. Most reproducers for cutting purposes are 
equipped with a non-synchronous motor, the speed of which is not 
constant over a period of time. In editing music tracks this has 
proved a handicap, as it is not easy to judge accurately the timing 
of music with a reproducer that is running faster or slower than the 
correct tempo. 

Sprocketless reproducers for quickly checking sound- tracks have been 
made available upon the market, but the film movement is by hand- 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received May 
21, 1937. 

** Warner Brothers Pictures, Inc., Burbank Calif. 




[J. S. M. P. E. 

power through the rewinds, and the suitability of such a device for 
reproducing music is questionable. To eliminate these objections, 
and provide a film reproducer that would run at a constant speed of 
90 feet per minute, without sprockets, clamp rollers, or other poten- 
tial film hazards, Major Nathan Levinson, Director of Sound at Warner 
Bros. Studios, suggested a device that has been worked out and placed 
in operation with gratifying results. 

The reproducer, a front view of which is shown in Fig. 1, consists 
essentially of a synchronous 110- volt motor geared to two polished 
steel rollers in such a manner that the peripheral speed of either roller 

FIG. 1 (a). Front view of editing machine. 

is 90 feet per minute. Between the two rollers is mounted an optical 
system, with exciting lamp and photoelectric cell, with a pair of aper- 
ture plates spaced so as to line up the film accurately with the optical 
system without scratching the film. In each plate, an aperture ap- 
proximately 0.09 inch square is cut, to pass the light-beam and mask 
the track in a manner similar to standard theater sound reproducing 
practice. The driving rollers are flanged at both ends to keep the 
film in line, and an additional guide-roller, although not absolutely 
necessary, is placed outside the right-hand driving roller to aid in 
steadying the film. 

Fig. 2 is a side view of the device, section A showing the details of 
the aperture plate and photoelectric cell, and section B the relation 
of the driving motor and gears to the driving rollers. Above each 

Sept., 1937] 



driving roller, and hinged to the frame in which the gears are housed, 
is an idler roller, recessed to avoid scratching the sound-track, and 

Fig. 1 (6). Upper front view of editing machine. 

held out of the way by springs when not in use. These rollers may 
be clamped down upon the driving rollers by gentle pressure of the 
hand; when neither roller is depressed, the film stands idle in the 

FIG. 2. Side view of reproducer: (A) details of aperture plate and photo- 
electric cell ; (B) arrangement of driving motor, gears, and rollers. 

aperture, the weight of the film on top of the driving rollers being in- 
sufficient to propel it one way or the other. 

If the film is to be reproduced normally, the left-hand idler roller 
is clamped down upon the film, and the device operates in the manner 

284 G. M. BEST [J. S. M. P. E. 

of a clothes wringer, bringing the film instantly to standard speed and 
direction. If the film is to be run backward, the right-hand idler 
roller is depressed, and the film is drawn past the aperture in back 
motion. Thus a section of film only a few frames in length can be 
drawn back and forth, and a single word or music phrase can be played 
again and again, until the cutter determines the exact point where 
he wishes to make a cut or split, whereupon he marks the film. If 
sections of film several hundred feet apart are to be checked in one 
reel, the motor can be cut off, and the film drawn through by hand 
until the next section to be checked is reached, using the set-up shown 
in Fig. 3. 

This arrangement is one designed for locating the correct position 

FIG. 3. Film-editing machine installation. 

for printer-light changes in variable-density release printing. In 
routine checking of the finished job turned out by the dubbing room, 
it is customary to run the separate picture and sound-track in the 
projection room, and to make notes of volume changes required to 
increase the volume range of the effects or music, and to take care of 
inaccuracies in the leveling of dialog by the dubbing mixer. These 
volume changes are obtained by the well known method of lightening 
or darkening the track during the printing operation, and the labora- 
tory requires accurate data regarding the location of each notch in 
the sound-track negative where the printer light is to be changed. 
Using the notes obtained in the projection room, the track and pic- 
ture prints are set up as shown in the photograph, with the automatic 
editing machine set between the footage counter and the right-hand 


rewind, and lined up so that the sound-track passes in a straight line 
from the left rewind through the counter and editing machine to the 
opposite rewind. The film can then be run through either by hand 
or motor power until the spots where volume changes are to take 
place have been located, and the section run back and forth until the 
exact spot for the notch is determined. The distance relative to the 
start mark is then noted upon a report, and the laboratory notches 
the corresponding negative at that spot. 

The output of the selenium photoelectric cell in the editing repro- 
ducer is connected to a three-stage amplifier similar to that used in 
all cutting room installations, and the sound is reproduced from a 
loud speaker set in a convenient place on the cutting table. Ad- 
mittedly, the film movement of the machine is not perfect, and a cer- 
tain amount of gear noise is heard in the loud speaker, but it does not 
interfere with either the intelligibility of speech or with the music re- 
production, and as the flutter is in synchronism with the motor and 
gear noise heard directly, the ear tends to discount the interference. 



Summary. Preparation of sound effects, music, and dialog tracks for dubbing 
requires accurate synchronization of each sound with the corresponding action. This 
is ordinarily accomplished by a preliminary step in which the synchronism of one 
sound-track at a time is checked against the action in a moviola, in which the picture 
is seen through a small viewing lens. 

The image being small, the accuracy with which synchronism may be checked is 
not good. Hence this is followed by a final step, in which the synchronism of all tracks 
is checked during rehearsals in the dubbing-room proper. Owing to the ponderous 
character of the dubbing machinery the latter process is quite slow and laborious. 
This paper describes the form and use of a machine that permits accurate synchronism 
of the various sound-tracks with the corresponding action, but with all the mechanical 
freedom of the usual moviola. 

The machine will accommodate six sound-tracks, with provision for controlling the 
output level from each, and may be instantly started, stopped, or reversed. The 
mechanical design facilitates threading and easy displacement of any sound-track by 
a known amount to bring it into synchronism. The action is projected upon a 
screen 4 l / 2 X 4 feet in size, which enables accurate observation of the degree of syn- 
chronism attained. 

An important gap has existed in the studio facilities for handling a 
picture in the stage between the editing and the dubbing processes. 
In the typical method of handling this intermediate stage, which we 
may describe as "dubbing preparation," a staff of cutters, deriving 
their general instructions from the music, editorial, and sound de- 
partments and from the director or producer, "build" the sound- 
tracks to provide supplementary effects and music required for a 
complete dramatic presentation of each reel of the picture. These 
cutters first review the picture in the projection room, making note 
of the comments of the director and producer and adding their own 
general notes, after which they obtain the necessary sound-tracks 
either from the library or from new recordings for this picture. In 
the course of getting the material together each cutter privately re- 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received May 
22, 1937. 

** Universal Studios, Universal City, Calif. 



views each reel several times to make sure that he is getting the right 

The work of assembling the sound-tracks into reels, accurately 
spacing them so that they will synchronize perfectly with the action, 
is usually done on sound moviolas, wherein the picture is viewed 
through a small viewing lens. The apparent size of the image is less 
than 2X3 inches, hence very close inspection is required to determine 
whether any given sound effect or musical beat is in synchronism 
with the action. Moreover such moviolas are usually provided with 
one (or not more than two) reproducing sound unit and hence the 
sound effects and music tracks must normally be checked one at a 
time. This is no handicap except where certain overlapping sounds 
are interrelated, but it often happens that this interrelation is just 
as important as the relation of either to the action for example, in 
the case of dance taps. 

Not only do errors creep in from such causes which must ultimately 
be discovered by viewing the picture and hearing the sound under 
more nearly theater conditions, but it is also common practice that 
the director, producer, musical director, and chief sound-effects cutter 
shall have an opportunity to review the whole effort under such con- 
ditions in order to pass judgment upon the merit of the material se- 
lected as well as to check the accuracy of its placement. 

It has been customary at several studios for this checking to be 
done on the dubbing channel itself. Aside from the fact that it ties 
up a good deal of dubbing channel and dubbing crew time, this would 
seem at first glance to be an ideal arrangement. However, a certain 
difficulty arises because of the ponderous nature of the dubbing chan- 
nel machinery, together with the fact that the sound accompaniment 
for many reels is very complex and requires careful and detailed re- 
view. When making this critical review of a reel it would be very 
desirable if we could run down through the first three or four points 
requiring comment or discussion, then stop to make adequate notes 
or decisions upon the points, then to continue through the next small 
portion of the reel, etc. Sometimes, in fact frequently, it is highly 
desirable to repeat a section several times until there is complete 
agreement as to the desirability of proposed changes. However, 
present-day dubbing machinery is not reversible, and the time re- 
quired to stop it, rewind, and re-thread five to eight sound-tracks 
and start again is prohibitive. For this reason it has been current 
practice to run the entire reel, making note of three or four most im- 



[J. S. M. P. E. 

portant points, then re-run it to confirm these points and pick up two 
or three others, after which it is sent to the cutting rooms for the nec- 
essary changes. However, it is a rather difficult matter to carry ac- 
curately in mind a large number of brief impressions, and the job of 
inspection just described becomes very superficial, particularly in the 
case of complex reels, so that it almost invariably happens that upon 
completion of the changes mentioned above (which may take a mat- 
ter of hours to identify and complete) there will still be found a num- 
ber of less important changes to make. Moreover it was not uncom- 

FIG. 1. View of the sound mechanism, showing method of threading. 

mon to find that the original decision for a change was made upon 
such superficial examination that the change proved undesirable and 
the original condition had to be restored. 

A great simplification of this problem, together with a substantial 
saving in time and improvement in accuracy can be accomplished by 
means of the dubbing rehearsal channel described in the following 
paragraphs. The heart of this channel is a combined action and 
sound reproducing machine capable of reproducing as many as six 
sound-tracks simultaneously, and which projects a picture 3 feet by 
4 feet in size, and yet has all the features of flexibility that distinguish 
the usual moviola. The machine runs as well in reverse as it does 

Sept., 1937] 



forward, reverses almost instantaneously, starts and stops readily, 
is very easily threaded, has provision for individual volume control 
of the several tracks, and produces quite satisfactory picture bright- 
ness and sound-quality. 

Fig. 1 is a general view of the sound-reproducing part of the mech- 

FIG. 2. View showing relation of sound and action units to 
motor drive. 

anism. Note that the six sound-sprockets are mounted on a single 
sturdy shaft approximately 1 inch in diameter with three-bearing 
support. A second main shaft drives 12 take-up spindles through 
as many belts. Threading is reduced to the simplest possible terms. 
Only the little pressure roller at the scanning point needs to be re- 
leased during threading, as the other four rollers are in fixed positions 
and are so shaped that the film may be slipped between them with 



[J. S. M. P. E. 

the simplest of motions. In spite of the fact that the six feed-reels, 
the six sound-sprockets, and the six take-up reels are respectively 
coaxial, the machine has been so designed that no obstructions are 
encountered in threading and the film may be placed upon or removed 
from the machine as easily when half the length of the film is on either 
reel as when one reel is empty. 

The little rectangular box in front of each sound-sprocket contains 
the exciter lamp, sound optic, and photocell. As seen in Fig. 2 the 
latter receives its light from a small concave mirror located immedi- 

FIG. 3.' Sound reproducer unit, showing optical path. 

ately behind the film, since the large sound-shaft prevents placing the 
cell itself behind the film as in conventional reproducers. The sound- 
sprockets are not keyed to the sound-shaft but are driven through 
retractable pins in the associated collars, which latter are keyed to the 
sound-shaft. Each of the 32-tooth sound-sprockets has eight holes 
to receive the retractable pin. Consequently, any one of the several 
sound-tracks may be advanced or retarded in one-frame intervals 
provided the machine is at rest. 

Fig. 3 shows the sound mechanism in its relation to the motor 
drive and the picture projector. The picture projector is a Simplex 
head in which the gate has been modified to permit reversal of the 
mechanism without buckling the film, and is driven from the slow- 

Sept., 1937] 



speed, three-phase synchronous motor through a crude but sufficiently 
effective elastic drive visible on the flywheel end. The need for this 
elastic coupling arises from the following considerations : 

Design of the sound mechanism is such that the synchronous motor 
is relied upon for constancy of speed, the two shafts of the sound re- 
producer being driven from the synchronous motor through a pair of 
precision gears. Maximum constancy of motor speed is attained by 

FIG. 4. Diagram of cell and mixer circuit. 

selecting a motor of several times the required power so that it will 
lock accurately to the line frequency and be nearly independent of 
variations in take-up loads, etc. Such a motor, even though provided 
with moderate starting resistances and fairly substantial flywheel, 
will accelerate the system much too rapidly for the Simplex projector, 
particularly because of the considerable inertia of the flywheel on the 
Simplex intermittent. 

Furthermore, the semi-instantaneous reversal of the system, which 
is so very desirable, still further aggravates the abuse to which the 
projector would be submitted were it not elastically coupled to the 

292 H. G. TASKER 

motor. The present combination of elastic coupling with resistors of 
low value connected in each leg of the three-phase motor make it 
possible to start, stop, and reverse the system with complete freedom. 

The transmission system of this machine is quite simple. A single 
amplifier of an inexpensive type provides all the amplification re- 
quired plus field supply for the loud speaker. Although individual 
volume control is provided for each channel there are no associ- 
ated individual amplifiers. Instead, the gain control is secured by 
varying the anode voltage of the photocells, as shown in Fig. 4. 
Small signal leakage which persists at zero anode voltage may be 
eliminated by throwing the key associated with each cell which ap- 
plies a small negative potential to the anode. All six of the cells are 
connected through a common circuit to the first tube of the amplifier. 
Exciter lamp supply is raw alternating current, and the fundamental 
hum frequency (100 cycles, since Universal Studio is equipped with 
50-cycle supply) is reduced approximately 20 db. by a very sharply 
resonant equalizer. The hum will be still further diminished when 
this machine, like our moviolas, is equipped for push-pull. 

A 500-watt projection lamp and watercell filter seen at the right of 
Fig. 4 supply the needed illumination for projection without danger of 
burning the film even when the projector comes to rest during re- 
versal. The usual fire shutter further diminishes the fire hazard. 

It is particularly helpful, when a timing error has been discovered 
by use of this machine, to be able to determine definitely which track 
is in error and by how much. By means of the keys provided in each 
of the mixer circuits all but one of the sound-tracks may be turned off 
and the remaining one checked accurately with the picture. If found 
to be satisfactory the next track is tried, and so on, and when the 
faulty track has been discovered it is put into synchronism with the 
action by the frame-shifting feature mentioned above, and the amount 
of shift is logged in the cutter's notes. Since errors of this sort usually 
occur in relatively short passages, it is readily seen how valuable the 
reversing feature of the machine may become. A fifteen-second pas- 
sage may be checked, reversed, checked again, reversed, and checked 
a third time in one minute and twenty seconds, and a synchronism 
change can be made and checked in one additional minute. 

The sound- quality, while not exceptional, is quite satisfactory for 
the purpose, and is limited more by the use of the ordinary type of 
dynamic loud speaker than by any other feature. The flutter, while 
readily noticed, is low enough so that it does not interfere appreciably. 



Summary. Special-effects cinematography furnishes a means of filming scenes 
that can not be filmed easily, safely, or economically by conventional methods. Various 
kinds of special-effects camera work are described, including multiple exposure, 
multiple printing, travelling-matte systems of printing and photography, the pro- 
jection background process, optical printing, and miniatures. The fundamentals 
of the processes are outlined, and the relations of the special-effects department to the 
studio organisation are discussed. 

The strictly technical details of the various special-effects processes 
have been fully covered in papers published from time to time in the 
JOURNAL. This paper will therefore seek to describe another and 
equally important phase of special-effects cinematography; namely, 
the relation of the work to the practical routines of commercial pro- 

In doing so it is necessary to review the development of this kind 
of work, especially in order to emphasize the tremendous difference 
between the magic-working trick cameraman of a few years ago and 
the special-effects engineer of today. The former was merely an in- 
genious craftsman ; his present-day successor is more nearly compar- 
able to a production executive than to anything else. In addition to 
being a technician and artist of high attainments, he must be a 
capable executive who can first sell to his studio the merits of special- 
effects work, and then organize and operate a department that is 
truly a studio within a studio. He must do so on an unfailing com- 
mercial basis, thus proving that he is saving his studio money every 
time he makes a special-effects shot. 

Special-effects cinematography has but one excuse for existing: 
it makes it possible to put upon the screen scenes that would by 
ordinary methods be either impossible or too difficult, dangerous, or 
expensive to produce commercially. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received May 
21, 1937. 

** Fred Jackman Process Corp., Burbank, Calif. 


F. W. JACKMAN [J. s. M. p. E. 

As an example of this, the part played by special-effects camera- 
work in filming an important feature made about a year ago at a 
major studio may be cited. The story of the picture involved several 
seventeenth century frigates and galleons. At least two ships had 
to be used; three would have been dramatically preferable. The 
greater part of the story hinged upon them and upon the bombard- 
ments, sea battles, etc., in which they participated. 

To construct full-sized ships and employ straightforward camera 
methods would have meant an outlay running well into six figures. 
Manning the fleet, providing the necessary camera ships, tugs, 
launches, and the like, and operating them at sea for the weeks or 
even months necessary to wait for the proper weather would have 
increased the cost of making these scenes to a sum far exceeding any 
budget practicable for filming the entire production. In addition, 
another sequence, in which a frigate shells and destroys an attacking 
flotilla of rowboats, would have been virtually impossible to film 
safely by ordinary means, for as the rowboats were destroyed, the 
men in them would have been thrown into the water, and an explosion 
capable of sinking a rowboat would have been transmitted by the 
water with force sufficient to injure and perhaps kill any men in the 
water within a hundred-foot radius. 

The scenes were therefore done by means of miniatures. Three 
miniature ships were constructed for slightly more than a thousand 
dollars apiece, and served quite as well as full-scale ships. Every 
bit of special-effects photography in the picture, including not only 
the ships and all the other miniatures, but also the routine special 
effects such as projected-background process shots, fades, dissolves, 
wipes, and the like, were delivered for less than half the cost of one 
full-scale ship. In other words, the difficult, dangerous, and prohibi- 
tively expensive scenes were filmed in perfect safety for approxi- 
mately one-quarter of the cost of merely constructing not using 
two full-scale ships. 

Time was saved as well as money. Done by ordinary methods, 
the sequence in which the rowboats were destroyed would have re- 
quired from four days to a full week of strenuous and expensive work 
with a full company. The miniature was filmed in half a day. The 
battle sequences, without allowing for the inevitable delays due to 
unfavorable weather, could not have been filmed conventionally in 
less than three weeks. The location of the -studio tank made it im- 
possible to shoot before 1 1 : 30 in the morning or after 2 : 30 in the after- 


noon; but even so, the whole sequence was filmed in four 4-hour days. 

Most important of all, the head of the special-effects department 
was able to plan both the technical and the economic aspects of the 
job with such accuracy that he was able to lay before the production 
executives an estimate guaranteeing the desired effects at a guaran- 
teed cost and within a guaranteed time. The scenes as they were 
actually used gave precisely the effect intended. They were achieved 
at a cost slightly below the original estimate, and delivered ahead 
of schedule. 

This case, while perhaps more spectacular than usual, is a typical 
example of the technical and economic precision of modern special- 
effects work. The modern special-effects engineer performs his work 
on the basis of thoroughly known principles, and he is able in ad- 
vance to predict both the result itself and the cost of obtaining it. 

In the earlier days of the industry, the few cinematographers who 
practiced what was then called "trick camera work" were regarded 
almost as so many magicians. They did not always know how suc- 
cessfully their magic was going to turn out, but they tried, and learned 
and in learning laid the foundation of today's knowledge and prac- 

One of the earliest principles they discovered was that of multiple 
exposure, followed by multiple printing. By keeping the camera 
motionless and making, say, two exposures with alternate halves of 
the frame matted out, a good number of mystifying effects could be 
performed. By matting out carefully selected portions of the pic- 
ture, an actor could be placed in positions of apparently great danger, 
heroically performing impossible feats. In some cases, too, the effects 
could be further extended by judiciously animating the actor, much 
as Mickey Mouse cartoons are animated today, and then superim- 
posing the animated action upon conventionally photographed back- 

Thanks in no small measure to the achievements of such engineers 
as A. S. Howell, for producing camera movements capable of un- 
varyingly accurate registration, multiple-exposure work has expanded 
to an amazing extent. In one such shot, made in the early days of the 
talkies by J. P. Fulton, no less than 64 successive exposures were 
made upon a single film. As the camera travelled about a cafe set, 
the faces of each of 32 different men changed momentarily to that of 
the hero. It is a tribute to the accuracy of the camera and to the 
craftsmanship of the cinematographer that this highly intricate 

296 F. W. JACKMAN [J. S. M. P. E. 

problem of multiple matting, timing, and registration was accom- 
plished perfectly on the first attempt. 

In due time, various forms of multiple printing grew to supplement 
and to a great extent to supercede multiple-exposure camera work. 
Many systems have been evolved, used and patented. Among them 
probably the best known is the Williams system, which involves the 
use of complementary moving mattes. The actor works in front of 
a blank background. From the shot, special negative and positive 
mattes are made and so intensified that in one matte the figure is 
simply a black silhouette against a clear background, while in the 
other the figure-image is clear and the background opaque. The 
mattes serve as masks through which in the first case the background- 
shot, and in the second-case, the action, are double-printed on a 
single film. 

More recently a number of processes have been evolved in which the 
background image is printed directly upon the negative of the action 
by running a toned print of the desired background through the cam- 
era in front of the unexposed film. The actors are illuminated by 
light of the same color as the toned background plate and perform in 
front of a plain background flat illuminated by light of a comple- 
mentary color. This prints the toned positive image upon the raw 
film in the camera, while the complementary colored light reflected 
from the actors passes through the toned image as if the latter did 
not exist. The Dunning process is perhaps the best known of these 
systems, but quite a number of others have been evolved, used, and 
patented; they differ mainly in details, such as the colors used, etc. 

At present, virtually all composite shots are made by the projec- 
tion background process, which is much simpler. A print is made of 
any desired background scene, still or moving, which is projected 
upon a large translucent screen of sand-blasted plate glass or cellulose, 
placed behind the foreground set and action. The background pro- 
jector and the camera that photographs the composite scene are elec- 
trically interlocked so that the shutters open and close synchron- 

It is obvious that any trace of unsteadiness in the projected picture 
in this process will destroy the usefulness of the whole composite 
scene. If the background plate is photographed in a camera that is 
not absolutely steady, the background of the composite scene will 
not be steady with relation to the foreground. If the background is 
printed in a printer that does not register perfectly, the same effect 


will result. If the projector does not maintain its registration micro- 
scopically, there will again be unsteadiness; and if the foreground 
camera is unsteady, this, too will be exaggerated in the composite. 

The obvious solution is to use pilot-pin registration throughout 
from background camera through the printer, projector, and com- 
posite taking camera. But that is only part of the answer. Modern 
projection background work demands such exactly accurate registra- 
tion that the pilot-pins must register through the same perforations 
throughout each operation. 

Motion picture photography is based upon the use of two types 
of camera, the Bell & Howell and the Mitchell, both of which are 
equipped with excellent pilot-pin registration systems. But one 
registers through two perforations above the frame, while the other 
registers two perforations below the frame. 

Clearly, if we photograph the background with a camera employ- 
ing one system of registration, and print or project it with equipment 
employing the other system, we can not attain microscopically per- 
fect registration in the projected picture. The error, viewed from a 
production viewpoint, may be negligible, but it is ample to spoil a 
process shot. For much the same reason certain designers of theatrical 
projectors who have offered projectors for process work equipped with 
side-tension registration only, have gravely underestimated the 
problem. Such a projector will undoubtedly be abnormally steady 
for theatrical use, but worthless for process purposes. 

The writer has found the commercial answer to the registration 
problem in the equipment designed and built for him by William 
Matz, of Hollywood, using the Bell & Howell system of pilot-pin 
registration throughout. Each unit is equipped with two interchange- 
able movements : one for use with background-plates photographed 
with the Bell & Howell camera, the other for use with Mitchell- 
photographed backgrounds. Each has its registering pins working 
through the same pair of perforations, in printing and projecting, 
that were used in photographing the original background negative. 

Equally important is the laboratory processing of both the original 
background negative and the projection prints made from it. Abso- 
lutely accurate control of gamma is necessary; fineness of grain is 
most desirable; and for best results it is desirable that there be no 
directional markings upon the film. Excellent results have been at- 
tained in the author's plant with the Roto-tank developing system 
engineered by Roy Davidge, which places the film upon a large metal 

298 F. W. JACKMAN [J. S. M. P. E. 

reel, sandwiched between spirals of a celluloid apron similar to those 
used in developing miniature camera negatives. The reel is laid 
horizontally in the tank, and oscillated 75 to 85 times per minute. 
This gives a nondirectional turbulence that produces no measurable 
directional markings, and furnishes a more clean-cut negative with 
greatly improved shadow-detail. Quite incidentally, the method re- 
duces the developing tune about 45 per cent, and permits diluting 
the developer considerably. There is no strain on the film, so ex- 
pansion and shrinkage are minimized. 

Some idea of the extent to which the projection background proc- 
ess is used today may be gained from the fact that in one important 
picture now showing Metro-Goldwyn-Mayer's Captains Courageous 
more than 80 per cent of the release footage was enacted before a 
process screen. Although this is an outstanding sea story, not one 
of the actors got nearer the ocean than a Culver City sound stage. 
Perhaps 15 per cent of the footage consists of atmospheric long-shots 
of the fishing boats; another 5 per cent, conventional intimate shots 
of the players; the remainder of the picture, including virtually all 
the important action, was filmed by means of projection background 
"process shots." 

Another important modern development is optical printing, which, 
as is well known, consists essentially in rephotographing positive 
prints of given scenes, frame by frame. Basically, the optical printer 
consists of a light-source, a positive film-moving mechanism usually 
using a specially modified Bell & Howell type of pilot-pin movement 
and a camera-head, also equipped with accurate pilot-pin registra- 
tion. Both Bell & Howell and Mitchell camera heads are used. 
Both film movements are driven from a common power source, and 
in most cases they may be operated at various speeds with relation 
to each other. That is, they may operate either to expose one or 
more frames of negative to each frame of positive, to skip alternate 
positive frames, to hold a given positive frame motionless for any 
number of negative exposures, or to reverse action by reversing the 
direction of the positive's travel with relation to the negative. 

In addition to making multiple-exposure and multiple-printed effects 
under the most controllable conditions, the optical printer regularly 
produces such transitions as fades, wipes, dissolves, turning-page 
effects, and the like by means of travelling mattes and variable 
optical elements. 

Moreover, the optical printer often serves as a means of doctoring 


ailing scenes. Vernon L. Walker has told of two such examples of 
how his department's optical printing staff saved the studio the ex- 
pense of retakes. In one picture an important scene was marred by 
a truck that passed through carrying an objectionable advertising 
sign. By means of the optical printer, the sign was blurred until it 
became no longer noticeable. In another picture, the star was sup- 
posed to crash in an airplane, escaping just as it caught fire and 
burned. He dropped from the cockpit and crawled to safety as 
scheduled, but the fire started too late, and did not burn to any ex- 
tent until he had crawled out of the picture. As the plane was com- 
pletely burned, a retake would have been expensive. The optical 
printer effectively moved the explosion and the fire up to the ap- 
pointed time at virtually no expense. 

The miniature is one of the very earliest of camera tricks, but is 
still of great importance today. Shots of ships at sea, naval battles 
and disasters, zeppelins and airplanes, trains and train-wrecks, and 
the like, are almost invariably photographed in miniature. Often 
when it is desired to establish a location in an atmospheric long-shot 
without necessarily using a stock-shot to establish the location as 
some particular one, a miniature setting is used. 

Making miniatures is far too complicated to be detailed here. 
However, in practice it is almost a matter of applying a mathematical 
formula : if the miniature is built to a certain scale, moved at a cer- 
tain speed, photographed from a certain camera position, lens angle, 
and camera speed, the result upon the screen can be predicted with 
mathematical accuracy. 

A miniature may be used as a projection process-background plate. 
In some instances, actual scenes may also be projected into a minia- 
ture, as was done in King Kong and other films. 

Another important use of miniatures is in what are called "set 
miniatures," in which parts of the set, sometimes foreground and more 
often background, are made in miniature. If designed and lighted 
in proper coordination with the design and full-scale photography of 
the set itself, they can not be detected as miniatures, and enhance 
considerably the illusion of size and depth, while effecting notable 

It may be well at this point to correct the impression held by many 
persons, even within the industry, that a miniature is necessarily 
toy-sized. It is not uncommon for a large miniature set to cover a 
complete stage and to be perhaps a hundred feet deep by forty or 

300 F. W. JACKMAN U. S. M. P. E. 

fifty wide. The miniature galleons referred to at the start of this 
paper were 12 feet long with masts 16 feet high. In another impor- 
tant miniature shot, the ship was so large that two men rode concealed 
within to operate necessary mechanical devices, and it was yet neces- 
sary to ballast the miniature ship with more than a ton of lead. 

The motion of miniatures is sometimes effected by self-contained, 
remotely controlled power units; but much more frequently minia- 
tures will be moved and controlled by concealed or invisible wires, 
permitting more accurate control. A miniature airplane, for instance, 
may have an electrically driven propeller, but it is usually made to 
take off, land, fly, and turn by invisible piano wires attached to the 
wing-tips and tail and working through pulleys on a T-shaped sup- 
port sliding along overhead wires. 

How is all this special-effects engineering coordinated with the 
regular operations of routine production? In the first place, the script 
for the entire production is ordinarily submitted to the head of the 
special-effects staff, who analyzes it and segregates the scenes that 
can advantageously be done by his department. 

With the scenes classified, he can then make accurate plans as to 
how they can best be filmed. He prepares the plans and submits 
them, with an itemized budget, to the studio production executives. 
When the budget is approved, he sets up a schedule by which the 
various special-effects scenes can be made that must coordinate with 
the schedule for filming the regular scenes of the picture. 

Generally speaking, the special-process scenes involving the actors 
are scheduled for the end of a picture's shooting period. This, how- 
ever, is all too often a very optimistic statement, for such scenes are 
habitually used as covering shots for every conceivable emergency 
from bad weather to the illness or injury of one of the principals. As 
such, the production manager may suddenly call for making scenes 
days or weeks before they are scheduled and is usually surprised 
if he finds that some other unit, working correctly to its own schedule, 
is occupying the special-effects department's facilities when he so 
unexpectedly demands them! There are also all the minor disturb- 
ances common to all production routines. Story changes may over- 
night remove process sequences one is prepared to shoot and replace 
them with totally unexpected ones. 

It is a tribute to the skill of all our studio' special-effects executives 
and their staffs that in spite of all this, the quality of all kinds of 


special-effects work has steadily improved, while the average cost 
per shot has steadily decreased with each succeeding year. The 
secret of this success is a matter of both knowledge and organization. 
A properly conducted special-effects unit, whether a department in 
a major studio or an independent special-effects contractor, must in- 
evitably be an organization of many specialists. The men must be 
specialists in much more than photography alone : practically every 
phase of studio activity must be represented. In addition to the 
stage crew of thoroughly competent operating and assistant camera- 
men, electricians, carpenters, and grips, all experienced not only in 
production but in special-effects technic, presided over by a trained 
Special Process Cinematographer or Director of Special-Effects 
Photography, there must be specialists in designing, building, and 
painting miniatures and full-scale sets and props; molders, riggers; 
art-directors, draftsmen, and the like. There must be laboratory 
technicians skilled in negative and positive film development, printing, 
multiple printing, optical printing, dye-toning and sensitometry. 
There must be cutters, projectionists, and clerical workers, all of 
whom know not only ordinary studio routines, but special-effects 
work. Over all must be a thoroughly experienced chief who must be 
at the same time a highly trained technician, a salesman, a director, 
and an executive. 

At his disposal must be not only the services of this varied and 
highly skilled personnel, but also a plant ample to take care of the 
physical requirements of the work. Finally, it is vital that he have 
access to an ample library of background scenes not ordinary stock 
shots from all over the world, accurately indexed and cross-indexed. 

This matter of organization is what marks the final difference be- 
tween the "black magic" pioneering days of special-effects cine- 
matography and today's commercial special-effects engineering. The 
early "trick cameraman" did much of his work almost single-handed. 
Today's special-effects specialist could probably do so as well; but 
he does not, because it is more efficient to utilize the advantages of 
organization. Without such organization, special-effects cinema- 
tography would still be possible, but it could not be the commercial 
asset it is today. 

In conclusion, the writer wishes to express his gratitude to the 
persons and studios who have cooperated in preparing this paper 
and the demonstration film; mentioning especially Byron Haskin 
and Warner Bros. -First National Studios, Farciot Edouart and 

302 F. W. JACKMAN 

Paramount Productions, and Vernon L. Walker and R-K-O Radio 


MR. MORGAN: What has happened to the problem of "hot spot?" 

MR. JACKMAN: A great deal of the credit for eliminating the "hot spot" must 
be given to a commercial screen manufacturer who has done a great deal of work 
on the subject. He has finally come to the conclusion that the "hot spot," or a 
great deal of the "hot spot," is caused by light transmitted through the screen. 
He has made a screen that I have been using during the past three or four years 
that is very much denser than the screens used previously. A high amperage 
is required, but there is very little difference in the temperatures, and I think 
the worries over the "hot spot" are eliminated. Previously we did not have an 
arc lamp that could handle the high amperage that is necessary, but I am now 
using a commercial lamp that presents no difficulties at all in getting a steady 
light up to 240 amperes. 

MR. BOWERS: What, if any, work has been done with Technicolor back- 

MR. JACKMAN: We have done some processing in Technicolor with varying 
results. It is easy to do airplane backgrounds, because we can take on enough 
color from the coloring in the film; but we have been able to do regular back- 
ground work with only small pictures, perhaps six to eight feet wide. 



Summary. A review of recent developments in 16-mm. sound, including techni- 
cal advancements and perfections contributing to raising the standards of illumina- 
tion and quality, and a discussion of the extent to which the limits of picture size and 
audience have been raised for large-audience performances. 

Adoption of the 16-mm. sound-film for education is discussed. Its function as a 
medium of instruction for general education of an extra-curricular nature and its 
use in the classroom as a corollary to text-book and oral instruction are treated. 

The relation between the 35-mm. and 16-mm. branches of the industry is discussed. 
What is the legitimate domain of 16-mm.? Limitation of both types of film, the 
most effective fields for each, and the encroachment of 16-mm. upon the entertainment 
field are brought out, and the possible effect upon the general trend of type of enter- 
tainment pictures is indicated. 

At the Spring Meeting of the Society held here two years ago, the 
writer outlined the trends in 16-mm. projection with special reference 
to sound. At that time it was predicted that the immediate expan- 
sion of the 16-mm. sound market appeared to be in industry, education, 
and in non-theatrical fields. It was pointed out that its use in small 
theaters would require producer cooperation, without which extensive 
use in this field would not be possible. 

It is interesting at this date to note that the predictions made two 
years ago are already on the way to realization. The sound picture is 
today definitely recognized as an important factor in industrial public- 
ity and advertising. The schools have accepted it as a valuable con- 
tribution to curricular activities as well as for general educational 
work. There is a growing use of 16-mm. sound as an entertainment 
medium in the non- theatrical field. 

The present-day types of 16-mm. sound-film and equipment show a 
marked advance over the types available two years ago. Constant 
improvements in laboratory processes have resulted in prints having 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received May 
26, 1937. 

** The Ampro Corporation, Chicago, 111. 


304 A. SHAPIRO [J. S. M. P. E. 

a wide range in frequency response. Equipment has been perfected 
so that it reproduces this wide range with negligible distortion. 
While illumination has been somewhat improved with the introduction 
of higher- wattage lamps and better optical systems, by far the greatest 
improvements have been in the increased volume and higher quality 
of the sound reproduction. There are now available at least two rec- 
ognized equipments that have power outputs of 40 watts or more, 
suitable for the largest auditoriums, that are sufficiently compact 
so as to be easily transportable and quickly set up for operation under 
widely varying conditions. These improvements have made it possi- 
ble to use 16-mm. sound in large auditoriums and halls that previously 
could be satisfactorily taken care of only with 35-mm. As today's 
improved illumination and sound have actually been designed for such 
auditoriums and halls, the user is not limited to the small audiences 
of yesterday. 

For commercial and industrial purposes the use of 16-mm. sound has 
almost entirely replaced 35-mm. There are now established a number 
of film producers who specialize in supplying pictures for this field. 
The pictures and sound are recorded on 35-mm. film in the usual man- 
ner and then reprinted on 16-mm. film. Reprints of such pictures are 
comparatively inexpensive and occupy one-fourth the space of 35-mm. 
prints. This makes it possible to transport the equipment easily from 
place to place, and set it up quickly for operation. Since no profes- 
sional operators are required, the performances can be put on by sales- 
men or company representatives. 

The effectiveness of such presentations is now generally recognized 
by industry. Among the largest users of this medium are the mem- 
bers of the automotive industry. In this field 16-mm. sound drama- 
tizes the stories of new models, tires, batteries, piston rings, etc., 
wherever there is a roof overhead and a crowd ready to listen. One 
large automobile manufacturer has several hundred 16-mm. sound pro- 
jectors constantly in the field dramatizing the story of its products 
before dealers and prospective customers. The shows are staged 
under all sorts of conditions, in dealers' display rooms, at club 
meetings, and local auditoriums. Wherever an audience can be 
brought together, 16-mm. sound is translating the advertisers' mes- 
sages to interested groups. 

The circulation possibilities of this kind of advertising are rather 
startling. For instance, Pennzoil has a 16-mm. sound picture called 
Farther, Faster, Safer which is a history of transportation development 

Sept., 1937] DEVELOPMENT OF 16-MM. SOUND-FILM 305 

in the United States condensed into twenty-five minutes of gripping 
events in motive history. The picture has been shown to students, 
business men, shop groups, service clubs, social organizations, and in 
schools, colleges, and churches, to a total of more than 2,500,000 active 
prospects for Pennzoil. 

There is every reason to believe that the industrial field will enjoy 
continued further expansion for 16-mm. sound. Its value as an adver- 
tising medium is now well established, and its low cost compares favor- 
ably with those of other established mediums. At the same time, 
no other medium makes possible such a vivid dramatization of a 
manufacturer's product as does the talking picture. The prospect's 
entire attention is held in focus by the picture and, with the addition 
of sound, is concentrated upon the sales story. 

It is in the educational field, however, that the most interesting 
developments have taken place with 16-mm. sound. Here the silent 
film had already made large inroads. Educators had recognized that 
the motion picture was a definite contribution in the field of pedagogy. 
The interest in visual education had resulted in the development of 
large libraries of educational film. Almost every subject taught in 
our grade schools and high-schools had been picturized, and compre- 
hensive film libraries had been developed. According to a tabulation 
published in July, 1936, by the American Council of Education, which 
covered only 9000 of the 242,000 schools in America, there were 6,074 
16-mm. silent projectors in use in these schools. They also reported 
having a total of 30,619 reels of 16-mm. silent film. As the investiga- 
tions from which these figures were obtained covered only a small por- 
tion of the schools of the country, it is quite evident that motion pic- 
tures have found extensive use in education. 

It is only natural that the educational field, having already found 
the motion picture a valuable tool, should be tremendously interested 
in the addition of sound to enhance its effectiveness further. Two 
things were required before 16-mm. sound could find wide acceptance 
in schools. First, there had to be equipment available, with the rela- 
tive simplicity of the silent projector for easy and clear reproduction ; 
second, an adequate sound-film library similar to the extensive silent 
library now available. 

In the early stage of this development, there was an inevitable delay 
due to the fact that purchase of equipment was deferred until an ade- 
quate library was produced, while the film producers were equally 
reluctant to invest in large libraries until there was a sufficient quan- 

306 A. SHAPIRO [J. S. M. p. E. 

tity of equipment available to make use of such libraries. In this way, 
there was a natural hesitation until enough machines and films were 
produced to give the entire movement an initial momentum. Once 
a substantial beginning was made, progress became extremely rapid, 
and machines and films were produced in ever-increasing numbers. 

One of the earliest producers of educational sound pictures on 16- 
mm. films, was Erpi Picture Consultants, Inc., of New York, N.Y. 
Their list of subjects now covers biological science, natural science 
physical science, social science, music, teacher training, and psychol- 
ogy. Most of these subjects are designed for high-school or college 
work. Erpi Consultants are now preparing 16-mm. sound-films for 
lower-grade work, and will undoubtedly continue to increase their 
library at a greater rate. Other organizations also have entered into 
the production of educational subjects so that a large library can be 
confidently expected in the near future. 

The increased use of talking pictures in schools has produced an in- 
teresting development in school architecture. While it is not neces- 
sary to build classrooms especially suited for showing talking pictures, 
nevertheless much can be done to improve the effectiveness of the 
presentations by providing suitable acoustics, means for properly 
darkening the room, and proper arrangements of seats for good vision. 
In a number of schools now being built through funds supplied by the 
Works Progress Administration, some of the classrooms have been 
designed so as to be especially adaptable to showing talking pictures. 
This recognition is significant in that it illustrates the importance 
with which the talking picture is now accepted by educators. 

That the schools are fast becoming aware of the possibilities of 16- 
mm. sound is illustrated also by the large numbers of courses for teach- 
ers and prospective teachers in visual education. Courses are being 
given not only in the technic of projector operation, but also in the 
more advanced methods of correlating pictures with textbook and oral 
instruction. It must be borne in mind that the use of talking pic- 
tures in education differs from its use in entertainment in that in edu- 
cation there is a fundamental learning process that takes precedence 
over every other factor. Repetition is of great assistance in the learn- 
ing process. The educational picture often required repetition of all 
or portions of it, particularly to emphasize the more difficult phases of 
the subjects being taught. In many cases the pictures are used as an 
introduction to the subjects, as focal points for discussion, and as 
means for reviews. 

Sept., 1937] DEVELOPMENT OF 16-MM. SOUND-FILM 307 

In the past it has been insufficiently realized that the primary prin- 
ciple of the educational picture is to educate, and this resulted in edu- 
cational pictures that had much more entertainment than educational 
value. Sufficient experience has now been had to justify viewing this 
problem from its primary function, that of a tool to increase the effec- 
tiveness of the educational processes. Here, it seems, is a field in which 
the pedagogue and the film producer can unite with great effective- 
ness in making valuable contributions to the field of education. 

Another phase of 16-mm. sound is its use in adult education and for 
the dissemination of general and specific information. Among the 
many Government bureaus that have adopted it for these purposes 
are the Civilian Conservation Corps., the Department of The Inte- 
rior, the Department of Justice, the National Park Service, the Naval 
Air Station, the Post Office Department, the Veterans' Administra- 
tion, the U. S. Naval Academy, the U. S. Department of Agriculture, 
the Federal Housing Administration, the Tennessee Valley Authority, 
and the National Archives. The demand for films by these many 
agencies has caused the Government to become a producer in its own 
right, and establish large staffs and well equipped studios for the 
production of sound pictures. Practically all the pictures are reduced 
to 16-mm. size for projection on 16-mm. portable equipment. 

An interesting application in the field of political campaigning was 
made in Sweden last year. The Peoples Party and the Socialist Party 
were the foremost contenders for votes. Each put into the field a 
battery of 16-mm. portable sound equipment that went barnstorming 
throughout Sweden. That the voters appreciated this refreshing 
change from the customary spellbinding is evidenced by the fact that 
the interest in the election and the total number of votes cast was 
greater than in any previous election. It is extremely gratifying to 
us in America that the equipment used by both parties was of Ameri- 
can manufacture. 

The use of 16-mm. sound for entertainment in the home has thus far 
been very limited. Lack of available rental films of suitable quality 
has retarded expansion in this field. With adequate film libraries there 
should be a vast market in the home field where picture programs 
can be selected to suit small-group requirements. 

We come now to the theatrical field. It had been expected that 
with the improvement in the 16-mm. sound reproduction, this instru- 
ment would be considered for use in small theaters of capacities of six 
hundred persons or less. The past two years, however, have not 

308 A. SHAPIRO [J. S. M. P. E. 

shown a decided trend in this direction. Theaters, whether large or 
small, running current productions, are still using 35-mm. equipment, 
in spite of the unquestionable savings not only in the cost of initial 
equipment, but in the cost of operation, cost of films, and their dis- 

In England, and in many other European countries, a number of 
theaters operate with 16-mm. equipment. The British Gaumont 
Corporation furnishes their current productions on both 35-mm. and 
16-mm. film, and, consequently, the theaters using 16-mm. equipment 
can show the same pictures as the theaters using 35-mni. equipment. 
This is also true of several other countries in Europe where income is 
important and the difference of cost between the two sizes of film 
has a direct bearing upon whether or not a theater can operate 

The principal reason for the non-use of 16-mm. film in the theaters 
of this country is that American producers as a whole are opposed to 
issuing their pictures on 16-mm. film. The entertainment library in 
this country is still very much limited to pictures made in the past, a 
great many of which were produced five or six years ago, with inferior 
recording equipment; and in reducing these pictures to 16-mm. 
prints, the resulting sound leaves much to be desired. This lack of 
suitable material, in the opinion of the writer, is the principal factor 
in the slow growth of the entertainment film in 16-mm. sound. 

In spite of this difficulty, however, a number of operators are using 
16-mm. sound-film for paid entertainments. They are generally road- 
men, who, like the industrial film user, carry their entire equipment 
and film programs from place to place, putting on performances in all 
sorts of halls and auditoriums. There is an insistent demand by these 
operators for more and better material, and undoubtedly this demand 
will ultimately be satisfied. Already, a number of distributing film 
libraries have opened in various cities and are doing a thriving busi- 
ness in the rental of films to such roadmen. 

We come now to the relation between the 35-mm. and 16-mm. 
branches of the industry. What is the legitimate domain of each? 
What are the limits of utility of the two sizes of film and the most effec- 
tive fields for each? A re-statement covering these points, in view 
of recent developments, is in order. 

In the field of industry, 16-mm. sound has definitely replaced 35- 
mm., except for showing advertising films in theaters. This, however, 
is of dwindling importance, as the paying public greatly resents having 

Sept., 1937] DEVELOPMENT OF 16-MM. SOUND-FILM 309 

advertising pictures foisted upon them as entertainment. In the 
wider and more legitimate use by industry for private and promoted 
distribution of their pictures to picked groups, the field is all with the 
16-mm. film. 

In education, the 16-mm. size had already been adopted before the 
introduction of sound. Here 35-mm. is definitely confined to large- 
auditorium installations where it is planned to run current productions 
of entertainment film. For teaching purposes, education has defi- 
nitely adopted the smaller film and recognizes 16-mm. sound as its 
most important visual aid. 

For adult education and propaganda the requirements are similar 
to those of industry in that the same equipment must be used in many 
locations of widely varying conditions. For such use, 16-mm. sound 
is a natural selection. 

In the theatrical field there is little likelihood that 16-mm. will re- 
place 35-mm. in theaters until the large film producers agree to release 
current productions at least shortly after their initial theatrical per- 
formances. Should the large film producers relax their policy of with- 
holding current releases, a tremendous outlet will develop for 16-mm. 
sound. In a previous paper, it was pointed out that of the 15,000 
theaters in America, about 70 per cent have capacities of 600 persons 
or less. A great number of these smaller theaters could utilize 16-mm. 
sound-prints provided current films were obtainable. Undoubtedly 
the several thousand theaters operating on the borderline between 
profit and loss could swing into the profit side with the economies possi- 
ble with 16-mm. There is also the foreign market, which is particularly 
suitable for 16-mm. sound, due to the fact that the average foreign 
theater has a relatively small seating capacity and the shipping cost of 
prints forms a considerable expense item. This could be reduced 
greatly with the use of 16-mm. prints. 

To summarize, it appears that the 16-mm. sound-film is adaptable 
to a number of uses. The 35-mm. film is limited to theatrical use, es- 
pecially to large theaters. In every other activity of motion pictures, 
the advantages are with the smaller film. Considerable exploita- 
tion has been done in the industrial field. The trend in schools is for 
at least one equipment in each school, and the future will undoubtedly 
see a large expansion in this field. Theatrical use of 16-mm. sound- 
film depends upon the attitude of film producers who control current 
productions towards releasing 16-mm. sound-prints. 


During the Conventions of the Society, symposiums on new motion picture appara- 
tus and materials are held, in which various manufacturers of equipment describe and 
demonstrate their new products and developments. Some of this equipment is de- 
scribed in the following pages; the remainder will be published in subsequent issues 
of the Journal. 



A new method of noise-reduction for variable-width film recording has been 
adopted by RCA and has been found to give excellent results. The recording 
optical system has been modified to incorporate a double-mask shutter and the 
galvanometer no longer receives biasing current. 

The shutter and optical system are shown in Fig. 1. The shutter, the recording 
aperture, and the associated lenses are incorporated in a single unit, which can 
be removed at will and re-installed without loss of adjustment. 

A schematic diagram of the optical system is shown in Fig. 2, where may be 
seen the exposure lamp, condenser lens, aperture, shutter masks, aperture pro- 
jection lens, galvanometer, slit converging lens, slit, ultraviolet filter, objective 
lens, and film. It will be noted that the recording aperture is a negative of the 
familiar triangular aperture used for biased galvanometer recording. The two 
shutter masks are drawn together when current is applied from the noise-reduc- 
tion amplifier. They separate when the current is reduced by the rectified signal. 
Since the images of the masks are moved vertically on the mechanical slit by the 
galvanometer, it is obvious that they must be parallel and perpendicular to the 
slit; otherwise, there would appear an audio-frequency modulation in the shutter 
portions of the sound-track. While this would not cause distortion, it is undesir- 

A comparison of the new symmetrical sound-track and the biased galvanometer 
track is shown in Fig. 3. It will be noticed that in the shutter track there is a 
change of recorded sound amplitude without displacement of either zero axis line. 
The unmasking action can be seen in the outer portions of the track as the modu- 
lation level increases. 

A new feature of the optical monitoring system permits viewing both speech 
modulation and noise-reduction action simultaneously. Increased light for moni- 

* Presented at the Spring, 1937, Meeting at. Hollywood, Calif.; received 
May 13, 1937. 

** RCA Manufacturing Co., Cam den, N.J., and Hollywood, Calif. 




toring and sharper focusing upon the card make visible high intermittent fre- 
quency peaks which have heretofore been difficult to see. 

The ability to observe the performance of a noise-reduction system accurately 
during recording has been found helpful. Interference between the speech wave 
and the masking action, if it should exist, can be discovered quickly and corrected 
without having to wait for the results of the day's work. These aids to operation 
assure more consistently good recording. 

In detail the method of monitoring is as follows: A portion of the output beam 
from the galvanometer is intercepted near the plane of the mechanical slit, and 
is reflected back. In this way a portion of the aperture is focused upon the moni- 

FIG. 1. Shutter and optical system. 

tor card. As shown in Fig. 4 movements of the shutter masks are seen as changes 
in height of the light-spot. Vibrations of the galvanometer are indicated upon 
the card by lateral movement of one edge of the light-spot. Three conditions are 
illustrated: (a) without modulation and with shutter closed, (b) modulation 50 per 
cent and shutter partly open, (c) modulation 100 per cent and shutter fully open. 
In the two latter cases the arrows indicate the magnitude of the modulation. 

With ultraviolet light for recording and printing, and because of the non-slip 
feature of the RCA printer, it is possible to maintain "standby" or "squeeze" 
lines approximately one and one-half thousandths of an inch wide on the film 
without fogging in the print. 

The noise-reduction amplifier gain is usually adjusted to make the shutter open 
fully and clear of the track with 80 per cent modulation. As for the dynamic 
characteristics of the shutter, the device is entirely controlled by the amplifier 



current. When properly adjusted, the time required for opening, with a suddenly 
applied signal fully modulating the sound-track, is 0.012 second. The remasking 
is accomplished in 0.16 second. This extended closing time avoids shutter modu- 
lation at low frequencies, as for example, when recording organ music. Under 
such conditions poor quality could result were the closing made faster. For 
class A push-pull the only limit to the speed of opening is the filtering of audio-fre- 
quency components from the rectified current. 

Fig. 5 is a schematic diagram of the shutter mechanism. The driving element 
consists of a reciprocating motor having a moving iron armature of the inductor 
type. This construction employs air-gaps of varying area instead of length, the 
chief features being good linearity over larger displacements and freedom from 

FIG. 2. Diagram of the optical system. 

high negative stiffness. The armature is coupled by means of a flexible steel 
cross spring to a pair of light-weight masks arranged to move in opposite direc- 
tions when the armature is displaced. These masks are drawn together by cur- 
rent from the noise-reduction amplifier during periods of no modulation, keeping 
practically all light out of the mechanical slit. The amount of unmodulated 
light reaching the negative sound-track is limited by the shutter masks, which 
move apart when a signal is applied to the system. When the limit of travel is 
reached and the shutter current approaches zero, the masks are in a position im- 
mediately to re-enter the slit as the modulation is reduced. This particular di- 
rection of current for operation is preferable. If the masks were opened by a ris- 
ing current the travel would be excessive for conditions of overmodulation and the 
closing would be delayed. The shutter can not be damaged by excessive modu- 
lation levels since there is then the least current in its windings. 

Uniform travel of both masks is assured by factory adjustment, and depends 

Sept., 1937] 



upon the relative length of span of the cross-spring either side of center. If the 
spring were longer on one side, that mask would move over a shorter distance. 
Equalizing is done on an optical fixture by loosening the clamping screw and slid- 
ing the spring in the required direction. The adjustment is then permanently 

To provide the necessary overall linearity of the shutter it was necessary first 
to determine over what range the armature alone would travel in a linear fashion. 
The drive ratio to the masks was then established, knowing the required displace- 
ment of the masks. It is obvious that the geometry of the cross-spring and 
attached masks is such that after a certain distance the movement becomes non- 
linear in such a manner that with uniform armature motion the mask travel 

Print shutter Print 

FIG. 3. Comparison of the new symmetrical 

sound-track and the biased galvanometer 


would be accelerated toward the end of the opening movement. A drive ratio 
was adopted so that the acceleration would begin as the armature motion dimin- 
ished. This increased the overall linear range. In Fig. 6 may be seen the open- 
ing displacement with current, showing that the linearity is well within the 
required limits. 

Another design problem was that of sufficiently reducing the moving mass to 
obtain a high natural frequency for the shutter, below which it would be controlled 
by stiffness and its excursions strictly governed by the amplifier current. The 
masks were made of duralumin and arranged to provide maximum coverage with 
minimum actual area of surface. The mass of the masks and the stiffnesses of 
the cross-spring and supporting hinges were proportioned to attain the desired 
natural period and yet retain good sensitivity. The complete shutter is tuned to a 
frequency of 140 cps. Damping is accomplished electrically by using heavy copper 



spools for the coils. This, plus the fact that the shutter resonates at a frequency 
well above the highest that can appear in the output current of the control amp- 
lifier, prevents "bouncing" or overshooting of the masks. 

One matter to which particular attention has been paid in the design of record- 
ing equipment is that of phasing for speech. It has been well established that 
the majority of speech waves and many sounds from musical instruments are not 
symmetrical, having lesser amplitudes during the half-waves corresponding to 

rarefaction of the air. This is because of 
the construction of the human voice 
mechanism. The lack of symmetry is 
plainly revealed in a variable-width sound- 
track. If proper care is not exercised 
in phasing the recording channel from 
microphone to galvanometer, including 

() No modulation 
Shutter cloied 


Shutter opening 75> 

(e) Modulation 100* 
Shutter open 

FIG. 4. Movements of the 
shutter masks as seen on 
monitor card. 



FIG. 5. Diagram of the shutter 

the noise-reduction amplifier, considerable interference can occur between the 
speech wave and the masking action. The requirements vary slightly depend- 
ing upon the type of track being made. For standard recording, the longer 
peaks of a non-symmetrical wave should extend away from the noise-reduction 
or shuttered portion of the sound-track. This applies also to biased galva- 
nometer recording. The noise-reduction amplifier is then phased to rectify the 
half of the wave containing the smaller amplitudes. 

How this appears in the new shutter type of track is shown in Fig. 7. At the 
left is an example of wrongly phased speech. The correct phasing is at the right. 
It will be noticed that in the latter track the large peaks project toward the cen- 

Sept., 1937] 



ter, where there is plenty of room, and away from the shutter or masked portions 
where the clearance is maintained at a minimum. 

Phasing speech for class A push-pull is not so important. With equal travel 
of both shutter masks a non-symmetrical wave might, however, interfere on one 
side of the track, depending upon the galvanometer polarity. It is possible and 
practicable to increase the travel of one mask a predetermined amount by means 
previously explained, to take care of average speech conditions, permitting the 
noise-reduction amplifier to continue rectifying the small side of the wave. Other 
methods have been proposed; for example, duplicate control amplifiers operating 
on opposite halves of the wave and driving isolated shutter masks. Most of the 


FIG. 6. Displacement vs. current. 

arrangements suggested made the entire system unnecessarily complex in return 
for a negligible improvement. 

Because of its inherent flexibility the new noise-reduction system can be used 
with a wide variety of sound-tracks, including special forms for original recordings 
as well as standard symmetrical track for release prints. 

Using the twin mask shutter in conjunction with a standard galvanometer as 
light-modulator, three different types of sound-track can be produced: 

(2) Standard symmetrical variable-width. 

(2) Class A push-pull variable-width. 

(3) Variable-density squeeze-track. 

Push-pull sound-film recording is gaining favor for original negatives, and of 


the available types the class A variable- width is considered preferable. Its ad- 
vantages are total elimination, by cancellation, of sibilant distortion commonly 
known as "zero shift," allowing, therefore, considerably wider latitude in develop- 

FIG. 7. Incorrect (left) and correct (right) 
phasing of speech. 

ment of both negative and positive than can be tolerated with standard track; 
and second, cancellation of any disturbances that might result from incorrectly 
adjusted noise-reduction equipment. 


MR . To WNSLEY : Will you explain by what means you accomplish proper phasing 
of the voice ? Suppose we have a track that is improperly phased ; what was done 
incorrectly in the recording to phase improperly? How are you sure you get the 
track in the proper phase? 

MR. BATSEL: The purpose of phasing the system in respect to a non-symmet- 
rical wave is to prevent excessive clipping by the shutter as it opens up the track. 

Phasing is accomplished by applying a non-symmetrical wave to the input of 
the system, and observing on the visual monitoring card the deflection of the gal- 
vanometer. Looking at the card from the position of the operator, the left-hand 
side of the light-beam represents the outside or maximum width of the track. 
Our practice in phasing the system is to have the long peaks of the non-symmet- 
rical wave point to the right of the monitor card, which on the track is to the cen- 
ter. The shutter amplifier is then phased to rectify this side of the signal. This 
practice permits full track for the long peaks and reduces clipping by the shutter 
as it backs out to clear the short half of the signal. 

It is known that the pressure side of the sound-waves produces the long half- 
cycle. By observation the microphone is likewise phased so that the long half- 
cycle deflects the galvanometer to the right, as seen on the visual monitor. 



It has long been recognized that duplicate negatives of sufficiently improved 
characteristics would be of value in protection against loss through damage to 
the original negative. Capstaff and Seymour 1 in an earlier publication have 
denned a perfect duplicate negative as one which would give prints identical 
in every respect to those obtainable from the original negative. Since that time 
two papers have been published 2 ' 3 giving the results of later work on photographic 
materials for duplicating work and methods for their use. 

Recent progress in the photographic emulsion field has made available new 
duplicating positive and negative films that possess in a high degree the char- 
acteristics most needed for making satisfactory duplicates, and excellent results 
from the standpoint of quality and graininess have been obtained through their 


The Duplicating Positive (emulsion series 1365) consists of a yellow dyed 
positive emulsion of medium contrast coated on a clear base. 

As shown in the curves in Fig. 1 suitable emulsion quality and development 
characteristics are obtained with the D-76 type of developer in the working gamma 
range of 1.0-1.5. There is practically no fog under normal conditions of use. 
It will be noted from the exposure scale that exposures somewhat greater than 
usual have been employed. The Eastman lib sensitometer gives proper ex- 
posures for process control purposes with multiple exposures of three to eight 
times. The sufficiency of exposure under any particular condition can be judged 
from the extent of the straight-line portion of the curve obtained. It is usually 
found that a triple exposure is sufficient when the lib sensitometer is set for the 
positive exposure condition with the exception that the light-filter is removed. 
The color-sensitivity of the Duplicating Positive emulsion is similar to that of 
Motion Picture Positive (series 1301) and, therefore, this film can be handled 
under the positive room illumination furnished by the Series Wratten safelight 
in an indirect fixture. 


The Duplicating Negative Film (emulsion series 1203) consists of a low- 
contrast panchromatic emulsion coated on a gray base of the same type as used 
for other negative film. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
May 20, 1937. 

** Eastman Kodak Co., Rochester, N. Y. 




The curves in Fig. 2 show that with the D-76 type of developer, proper emulsion 
quality and control of contrast are obtained in the recommended gamma range 
of 0.6 to 0.7. Emulsion 1203 is exposed sufficiently when a single exposure is 
given with the lib sensitometer at the normal positive setting. 

The distribution of spectral sensitivity is shown by the spectrogram in Fig. 3, 
the indications of which will be found useful for comparison with those of other 
emulsions, as shown on page 64 of the handbook of "Motion Picture Laboratory 
Practice." 4 This extended color-sensitivity gives the Duplicating Negative 
emulsion additional speed which is of considerable advantage where optical 
printing is employed, and particularly in the case where a master positive is 
dense. While the panchromatic emulsion is sensitive to all portions of the visible 


a eo 




h I.6O 

2 iao 

. 100 



FIG. l(a). Exposure curves of Duplicating Positive 
(emulsion 1365), with D-76 developer. 

spectrum, the green Wratten Series 3 safelight has the advantage of visual 
efficiency at the level of illlumination employed in photographic darkrooms. 
However, the speed of the Duplicating Negative emulsion is such as to permit 
illumination levels somewhat higher than are obtained conveniently by the use of 
the standard Wratten Series 3 filter. The most satisfactory way of obtaining 
the required increase in illumination is to substitute a sheet of tissue paper for 
the regular-weight white paper used in the Series 3 filter. The darkroom illumi- 
nation should be tested with the Duplicating Negative Film in the manner recom- 
mended in the handbook of "Motion Picture Laboratory Practice" 4 (p. 139). 

It will be observed that both the Duplicating Positive and Duplicating Negative 
have a very fine grain structure and give a somewhat transparent brownish 
image. The effective density of such a deposit when printing by contact on 
Motion Picture Positive Film is considerably greater than that indicated by 

Sept., 1937] 



visual densitometry. Consequently, the printing -contrast under this condition 
is greater than it appears to be by visual or densitometric comparison with a 
Super X (emulsion 1227) negative, for example. The values for density were 
determined with a visual densitometer, usually the Eastman densitometer. The 
effect of this condition on densitometry and the selection of gamma values is 
treated in more detail below. 

Both the Duplicating Positive and Duplicating Negative are capable of re- 
producing fine image detail. 


The master positive should be the first print made from the original negative 
in order to serve as an insurance against loss of or damage to the original negative 
during editing, cutting, or printing. 

(a) Printing. Good reproduction of tone in the duplicating process is assured 

FIG. 1(6). Time-gamma curve of Duplicating 
Positive (emulsion 1365), with D-76 developer. 

if the exposure is selected in such a way as to utilize the region of proportional 
reproduction indicated by the straight-line portion of the characteristic curve. 
In this region the densities in the master positive bear a direct relation to those 
in the original negative. While it is possible to obtain acceptable tone repro- 
duction without confining exposures strictly within this range, the manner of 
procedure in the two steps in the process must be determined by trial and error. 
No simple systematic procedure can be prescribed. Therefore, it is assumed, 
for the purpose of description in this paper, that the region of proportional 
reproduction is utilized exclusively. 

Printing exposure requirements for the master positive are illustrated in the 
following example: An original negative having a maximum density of 1.40 
required an exposure of approximately 400 meter-candle-seconds to produce the 
required minimum density in the master positive of 0.70 at a gamma of 1.25 
under recommended development conditions. This exposure is given in 0.12 
second by a 500-watt 110- volt monoplane filament lamp operated at approxi- 
mately 85 volts and located at a distance of 10 inches from the raw film. These 
conditions refer to the case of contact printing at 15 feet per minute. The 



exposure required depends, of course, upon the emulsion speed realized under 
the actual development conditions for the Duplicating Positive. 

If the means of controlling exposures in printing the master positive provides 
regular log exposure increments from step to step equal to those used in the 
equipment for exhibition release printing, then the printer settings for master 
positive printing can be obtained from those found necessary for a "balanced" 
release print made from the original negative. It is necessary only to establish 
the exposure level which will produce a sufficiently high minimum density for 
successful tone reproduction, that is, about 0.70. If this procedure is followed, 
the scene to scene variations in density are largely disposed of and a minimum 
of adjustment will be required in the succeeding operation to produce a duplicate 
negative that has uniform printing quality. 

When operating conditions are being selected for the duplicating process the 
effect of an adjustment at any point in the procedure should be tested by carrying 


FIG. 2(o). Exposure curves of Duplicating Negative 
(emulsion 1203), with D-76 developer. 

the duplicating process through to completion. Results should be judged only 
by examination of prints from the original and duplicate negative, because visual 
examination of the Duplicating Film images may be misleading for the reasons 
stated above. 

As stated in previous publications, 2 ' 3 the duplicating process requires printing 
equipment capable of giving good definition and uniformity of exposure. A 
diaphragm or matte type of light control is to be preferred to one involving 
change in lamp current and, consequently, changing quality of illumination. 
However, the effect of moderate changes in lamp current upon photographic 
contrast is not very serious with emulsions 1365 or 1203. 

(b) Processing. Duplicating work requires the use of the best possible 
processing equipment in order to hold such imperfections as unevenness below 
a tolerance limit. The print from a duplicate negative shows the accumulated 
imperfections of four steps in processing as compared with two in the case of a 
print from an original negative. 

Sept., 1937] 



The curves shown above were obtained under the manufacturer's standardized 
processing treatment 8 with D-76 developer of normal strength. The D-76 type 
of developer gives good tone quality and permits convenient control of develop- 
ment velocity through modifications of the nature suggested in an earlier publica- 
tion. 6 These modifications are also discussed on page 90, et seq., of the handbook 
of "Motion Picture Laboratory Practice." 4 In most motion picture processing 
machines a developer of somewhat less activity than normal D-76 is preferable. 
Good results can be obtained by dilution to two-thirds strength, for example, or 
as suggested in the publication referred to. In order to obtain the best processing 
control, it is desirable both for the Duplicating Positive Film 1365 and the 
Duplicating Negative Film 1203 that processing be carried on in a developer 
maintained at a uniform degree of exhaustion and replenished to maintain a 
constant rate of development. 

In selecting gammas for the master positive and duplicate negative it is as- 

FIG. 2(6). Time-gamma curve of Duplicating 
Negative (emulsion 1 203), with D-76 developer. 

sumed in general that no modification of quality is intended to be effected through 
the use of the duplicating process. Such modifications are easily made but are 
considered as the exceptional case. 

In the experimental work on the new type of duplicating emulsions tests were 
made on the effect of using a high gamma for the master positive and a low gamma 
for the duplicate negative as compared with the use of equal gammas in the two 
steps. Graininess was found to be less for the high-gamma-low-gamma method 
than for equal gammas. This confirms previous work 3 on other emulsions. 
Master positive gammas between 1.1 and 1.5 were found suitable for the master 
positive with duplicate negative gammas in the neighborhood of 0.6 to 0.7. 
Recommendations are made below on the basis of a value of 1.25 for the master 
positive. A higher gamma in the master positive has the effect of procuring 
somewhat greater effective emulsion speed in the master positive stage and, 
generally speaking, a corresponding increase in the exposure required for printing 
the duplicate negative, because of the increased master positive density. For 
this reason it is not found advantageous to use higher values for the master posi- 
tive gamma. 

The yellow dye is discharged very rapidly from the emulsion during develop- 



ment. While it imparts a temporary coloration to the developer, it does not 
impair the properties of the developer. 

A good hardening fixing bath such as F-25 is suitable for use with emulsion 
1365. In the fresh fixing bath, fixation is complete in 2 minutes. Hardening 
of this emulsion takes place rapidly and becomes excessive if treatment is pro- 
longed greatly beyond this time. This should be avoided because the emulsion 
surface is water repellent and, therefore, liable to water spotting. If, because 
of necessarily longer time of treatment or because of the constitution of the fixing 
bath, hardening is excessive, this should be corrected by suitable modification 
of the bath. 7 ' 8 Fixing baths in an extremely exhausted condition should not 
be used for duplicating work. 

Hypo and other soluble substances are removed rapidly from the 1365 and 
1203 types of emulsions during washing. On account of the value of any master 
positive or duplicate negative as a permanent record, the washing should reduce 
the concentration of hypo should be reduced to a very low magnitude by thor- 
ough washing so as to avoid the danger of image fading. 9 

(c) Drying. On account of the smooth glossy condition of the surface of 
emulsions 1365 and 1203 and the inherent rapidity of drying, any maladjustment 

FIG. 3. 

Spectral sensitivity of Duplicating 
Negative Film. 

in the drying operation can cause drying spots. The quantity of "loose" water 
left on the emulsion surface after squeegeeing must be very slight or droplets 
form with drying lines or spots as a consequence. However, a careful adjustment 
of standard squeegeeing equipment should suffice to give good results. The 
1365 and 1203 emulsions are dried in one-third to one-half the time required for 
Motion Picture Positive Film under the normal drying conditions for the latter. 
The drying rate should be diminished by lowering the dry-bulb temperature, or 
reducing the air velocity, or by raising the humidity in any convenient manner. 
Upon leaving the drying cabinet, the film should be in a suitable condition for 
handling in succeeding operations and, consequently, should have a moisture 
content of equilibrium with an atmosphere of about 60 per cent relative humidity 
at room temperature. This condition should be attained in about 15 minutes 
of drying time. 


(a) Printing. As indicated above for the master positive, it is assumed that 
the 1203 duplicate negative is to be exposed in such a way as to utilize the region 
of proportional tone reproduction characterized by the straight-line portion of 
the density-log exposure curve. For a master positive having a maximum den- 
sity of 1.95, an exposure of 150 meter-candle-seconds is required to produce the 


minimum density of 0.45 at a development gamma of 0.65. These values have 
been determined for the use of a master positive of the density and contrast 
recommended above. The resultant duplicate negative will have a maximum 
density of 1.30, a minimum density of 0.45, and a density scale of 0.85 as com- 
pared with 1.40, 0.40, and 1.0 for the corresponding values in the original nega- 
tive. The difference in the density scale of the original and duplicate negatives 
results from the difference in the visual and effective printing densities of the 
Duplicating Negative Film. This type of discrepancy is observed with duplicate 
negatives made with materials used previous to the present time, but is of lesser 
magnitude. However, it has no disturbing effect in the duplicating operation 
after standards are once set up for the processing solutions which are used. Con- 
trol in making the duplicate negative is maintained by means of sensitometric 
strips exposed on the 116 sensitometer in the manner indicated above. 

In establishing the standard operating conditions the use of a typical set of 
data as shown in Table I should be convenient. It will be noticed that the gamma 


Exposure and Development Data 

Minimum Maximum Density 

density density scale 

Original Negative 0.40 1.40 1.00 

Master Positive 0.70 1.95 1.25 

Printed on Emulsion 1365 

Step Printer: 15 Ft. per Min. 

500-watt lamp : 85 volts 

Meter-Candle-Seconds: 400 
Developed in D-76d, 2 /s strength, 

70F. 4 3 / 4 Min. 
Gamma: 1.25 

Duplicate Negative 0.45 1.30 0.85 

Printed on Emulsion 1203 

Step Printer: 15 Ft. per Min. 

500-watt lamp : 60 volts 

Meter-Candle-Seconds: 150 
Developed in D-76d, 2 / 3 strength, 

70F. 3V Min. 
Gamma: 0.65 

product obtained from the master positive and duplicate negative gammas 
(lib sensitometer), which might have been expected to be unity, is actually 
about 0.81. 

If local conditions favor the use of other developers or different gammas at 
either step in the process, then control values should be determined for those 
conditions by carrying test samples through the complete duplicating process. 
Adjustments should be made in one step or the other until proof prints from the 
original and duplicate negatives developed together indicate equal effective 
printing contrasts in those negatives. 


If it is considered advisable to utilize portions of the density-log exposure 
characteristic lying outside the straight-line portion, then new standard control 
conditions must be adopted. When a change of this kind is made in the master 
positive exposure, then compensatory changes in the development of the master 
positive and the duplicate negative and in the exposure of the duplicate negative 
are necessary, if an acceptable reproduction of tone is to be retained. 

In working out the new conditions discussed in the preceding paragraph, a 
density step-tablet should be attached to the original negative and should be 
reproduced with picture tests in all succeeding steps. Prints from the tablets 
in the original and duplicate negatives will furnish data for reproduction curves 
prepared in the manner suggested in a previous paper. 3 A more complete 
analysis of the effect of changes in procedure in any step can be obtained through 
the use of a method for the study of tone reproduction described by L. A. Jones. 10 

As stated in connection with the printing of the master positive, the printing 
equipment must be capable of giving uniform exposure and good definition. It 
is anticipated that the process of printing the duplicate negative will frequently 
involve optical printing and that it may be required to produce duplicate nega- 
tives of equal quality by optical and contact printing. With optical systems 
where illumination is strongly specular the contrast obtained in projection 
printing is greater than that in contact printing. When printing from a 1365 
master positive this increase in contrast may not be of the same magnitude as 
with materials previously used. It may be necessary, therefore, to make an 
adjustment in the development contrast of the duplicate negative or to modify 
the illumination system of the optical printer in the manner described by Tuttle 
and Young 11 in order to obtain the required agreement in contrast. As stated 
previously, the printing contrast of a duplicate negative must be judged from 
the prints which it yields in comparison with prints from the original negative. 

When the negative is exposed in such a way as to utilize the straight-line por- 
tion of the Duplicating Negative characteristic, the duplicate negative will 
usually have greater effective printing density than an original negative in which 
very low densities are found. 

(b) Processing. As in the case of the Duplicating Positive, a modification 
of the D-76 developer can be used to advantage. Unless the development gamma 
for the duplicate negative is greatly different from that recommended, the same 
developer can be used as for the master positive. If a different developer activity 
is required for this or other reasons, it can be obtained in the manner suggested 

The developer used for Duplicating Negative Film should not be permitted 
to vary greatly in its exhaustion level. If it is attempted to compensate for 
extremely different degrees of exhaustion by varying the time of treatment, the 
image color may be affected in such a way as to alter the effective contrast for 
a stated development gamma. 

In a fresh fixing bath of the F-25 type, emulsion 1203 is fixed completely in 4 
minutes. As recommended previously, necessary steps should be taken to avoid 
excessive hardening. 



A duplicate negative is acceptable for release printing only if scratches, abrasion 
marks, dirt spots, and unevenness in density accumulated throughout the process 
are held to the lowest possible amount by the exercise of due care in handling 
and processing operations. It is recommended, therefore, that all necessary 
aids to better processing such as those involving supplemental agitation in the 
developing bath and the use of an acid stop-bath be adopted. 

Cinching can be diminished by carrying out all winding operations in sufficiently 
moist clean air and by winding firm rolls. Duplicating films show finger prints 
and other handling marks rather prominently on account of the smooth glossy 
emulsion surface. 

Cleaning operations should be carried out in such a way as to avoid solvent 
spotting or the condensation of atmospheric moisture. Also, attention should 
be given to the equipment used for cleaning and to the choice of cleaning pads. 


1 CAPSTAFF, J. G., AND SEYMOUR, M. W. : "The Duplication of Motion Picture 
Negatives," Trans. Soc. Mot. Pict. Eng. (Feb. 1927), No. 28, p. 223. 

2 IVES; C. E., AND HUSE, E.: "Notes on Making Duplicate Negatives," 
Trans. Soc. Mot. Pict. Eng. (1928), No. 34, p. 382. 

3 CRABTREE, J. I., AND SCHWINGEL, C. H.: "The Duplication of Motion 
Picture Negatives," /. Soc. Mot. Pict. Eng., XLX (July, 1932), No. 1, p. 891. 

4 "Motion Picture Laboratory Practice and Characteristics of Motion Picture 
Film," Eastman Kodak Company (1936), 310 pp. 

6 JONES, L. A., RUSSELL, M. E., AND BEACHAM, H. R.: "A Developing Ma- 
chine for Sensitometric Work," /. Soc. Mot. Pict. Eng., XXYIII (Jan., 1937), 
No. 1, p. 99. 

8 CRABTREE, J. I., AND CARLTON, H. C.: "Some Properties of Fine-Grain 
Developers for Motion Picture Film," Trans. Soc. Mot. Pict. Eng., XIII (1929), 
No. 38, p. 406. 

7 CRABTREE, J. I., AND HARTT, H. A.: "Some Properties of Fixing Baths," 
Trans. Soc. Mot. Pict. Eng., XIII (1929), No. 38, p. 364. 

RUSSELL, H. D., AND CRABTREE, J. I.: "An Improved Potassium Alum 
Fixing Bath Containing Boric Acid," J. Soc. Mot. Pict. Eng., XXI (Aug., 1933), 
No. 2, p. 137. 

8 CRABTREE, J. I., PARKER, H., AND RUSSELL, H. D. : "Fixing Baths and Their 
Properties." (To be published.) 

9 CRABTREE, J. I., AND Ross, J. F.: "A Method of Testing for the Presence 
of Sodium Thiosulfate in Motion Picture Films," /. Soc. Mot. Pict. Eng., XTV 
(April, 1930), No. 4, p. 419. 

10 JONES, L. A. : "On the Theory of Tone Reproduction with a Graphic Method 
for the Solution of Problems," /. Soc. Mot. Pict. Eng., XVI (May, 1931), No. 5, 
p. 568. 

11 TUTTLE, C., AND YOUNG, D. A.: "Illumination in Projection Printing of 
Motion Pictures," J. Soc. Mot. Pict. Eng., XTX (July, 1932), No. 1, p. 842. 



In the early part of 1935 the Agfa Ansco Corporation, responding to a general 
demand by the motion picture industry for wider specialization of film products, 
manufactured and marketed an infrared-sensitive negative material designed 
principally for the purpose of photographing night effects in the daytime. Dis- 
semination of technical information pertaining to the practical application of 1 his 
product was undertaken, and the film gave promise of supplying the means of 
eliminating, to a certain extent, the economic disadvantage of actual night photog- 

Production use, however, brought to light emulsion characteristics that, al- 
though of decided utility in certain phases of motion picture work, did not lend 
themselves well to the more intimate details required when photographing close- 
ups of characters in standard panchromatic make-up. 

As a direct result of this experience a new infrared negative, referred to as Type 
B, was brought forth in December, 1936, and has, since that time, fulfilled all film 
requirements necessary to the successful production of night scenes in the day- 

The physical properties of this new material, such as base and anti-halo treat- 
ment, are similar, of course, to those of all motion picture negative films. It has 
been designed to meet standard laboratory processing requirements, and the 
keeping quality, under ordinary storage conditions, has proved to be excellent. 

In general speed the film is nearly equal to that of Superpan when both types 
are exposed without filters. It is necessary, however, in order that infrared-sen- 
sitive negative fulfill the function for which it is designed, to expose only with red 
filters which absorb the blue rays. Practical experience has indicated that the 
most useful range of filters lies between the Wratten Monobrom 21 and the 29 F. 
The filter-factor for these blue-absorbing and red-transmitting filters has been 
found, by sensitometric and practical tests, to be from four to five. The use of 
deeper red filters adds in no way to the pictorial quality and merely prolongs the 
time of exposure. In many instances, however, filters as light as the Wratten 
15G have been found suitable, although they transmit some ultraviolet in the 
region of 3000 A. 

Fig. 1 is a wedge spectrogram comparison of Superpan, the original infrared 
type, and the new Type B infrared, and illustrates the characteristic color-re- 
sponse of each material. Attention is pointed to the red and infrared-sensitivity 
of the Type B material, which reveals a maximum at approximately 7400 A. The 
sensitizing pattern of this type permits the use of relatively light red and even 
heavy yellow filters, due to the lack of response in the green-yellow regions. 

*Presented at the Spring, 1937 Meeting, at Hollywood, Calif. ; received May 
15, 1937. 

**Agfa Ansco Corp., Pacific Coast Technical Division, Hollywood, Calif. 


Fig. 2 shows graphs of sensitometric time-gamma curves comparing Superpan 
and the new Type B infrared negative, and reveals the comparable ratio of con- 
trast obtained with these two types at various developing times. This similarity 
is particularly desirable when photographing close-ups or when it is necessary to 
match scenes photographed on regular panchromatic negative. 

Principles of lighting technic pertaining to booster lights ordinarily employed 
in producing night effects in the daytime, have been found entirely applicable 
when using this type of film in conjunction with appropriate filters. Exhaustive 
tests conducted to observe the effect of panchromatic make-up, reveal that the 
only alteration necessary is a slightly darker lip rouge produced by the addition 
of a small amount of blue or brown pigment. 

Set practicals such as street lamps, automobile headlights, etc., are rendered 

FIG. 1. Spectrogram comparison of (A) Superpan negative; (B) the origi- 
nal infrared type; and (C) the new Agfa Type B infrared. 

far more realistic than has heretofore been possible with ordinary panchromatic 
film. Window lighting must be done, of course, with the aid of artificial lights, 
as in the past, but reveals a far more sturdy effect. The use of either reflectors or 
booster lights for close-up modelling has been found to be entirely satisfactory, 
producing soft halftones with the required contrast when applied in the same 
proportion as for panchromatic negative. 

Pictorial long shots in which there is considerable green foliage are recorded 
with particular charm due to the infrared reflection of chlorophyll, the green color- 
ing matter of plants and leaves. The effect produced by this substance in con- 
junction with this type of film when viewed upon the screen is very similar to that 
viewed actually on moonlight nights. 



Superpan Negative 

toy Relative Exposure 

Superpan Negative 

with Blue -extinction filter 


Lay Kf/ativf Expoturt 

Infro R,d,lyp,B 

Developed in 617 

ln<ra Red, tifpt B 

EpoHd Blue Erti-dio" 

f.lter. De^loped in B 17 

ioy **/ frpctur* Log Ktlatht l*poturt 

FIG. 2. Sensitometric time-gamma curves comparing Superpan and the new 
Type B Infrared film. 



<O IS* to' 25 

Developing Time 

Infra Red, type B 
Developed in B-17 

I 2345678-9 

oy Relative Exposure 

FIG. 3. Exposure and fog curves of Type B Infrared film. 


Haze penetration properties, due to atmospheric absorption of short-wave 
length radiation and the recording of the longer rays, make it possible to photo- 
graph scenes of extreme beauty under what would ordinarily be regarded as ad- 
verse conditions. Many economic possibilities have been exploited by pro- 
ducers, who have long recognized the financial disadvantage and artistic short- 
comings of night shooting. In numerous instances the intelligent application of 
this new medium has not only resulted in a saving of light and labor, but has cir- 
cumvented, as well, the ever-present danger of illness to important players when 
heavy night schedules are necessary. This general utilization has included paint- 
ing permanent street sets a blue-gray color so that a more realistic night effect 
could be produced with infrared negative which, at the same time, would not 
hinder the use of panchromatic for the day scenes. 

Infrared negative involves no laboratory problem, as processing may be carried 
out in the usual manner without special treatment or alteration in developing 
times. The time-fog density curve shown in the upper left-hand corner of Fig. 3 
reveals only a slight increase of fog with extended developing times. The ordinary 
green safelight in general use for processing panchromatic film, although trans- 
mitting some infrared rays, has been found by practical experience to be satis- 
factory with the usual precautions. 

In conclusion it is hoped that this addition to motion picture film material will 
stimulate and encourage the imagination of the practical technician so that in the 
future he will more readily demand of the manufacturer other special types en- 
abling him not only to enhance the beauty of his productions but also to overcome 
successfully the technical problems still awaiting solution. 



The editors present for convenient reference a list of articles dealing with subjects 
cognate to motion picture engineering published in a number of selected journals. 
Photostatic copies may be obtained from the Library of Congress, Washington, D. C., 
or from the New York Public Library, New York, N. Y. Micro copies of articles 
in those magazines that are available may be obtained from the Library of the U. S. 
Department of Agriculture, Washington, D. C. 

American Cinematographer 

18 (July, 1937), No. 7 

Hessercolor Is All Set to Enter Still Market (p. 273). G. BLAISDELL 
Reeves Combines Light Tester and Sensitometer 

(p. 282). 

Bell & Howell Installs Vaporate Film Treatment 
(p. 299). 


10 (July, 1937), No. 7 

Standards in Television (p. 10). H. M. LEWIS 

The Resonoscope (p. 17). 
Amplifier Measuring Technic (p. 18). E. F. KIERNAN 


13 (June 15, 1937), Nos. 9/10 

Das Einmaleins des Rechnens in Dezibel, Phon und 
Neper (A Table of Computations in Decibels, Phons 
and Nepers) (p. 91). P. HATSCHEK 

International Photographer 

9 (July, 1937), No. 6 
Color (p. 5). E. GIBBONS 

International Projectionist 

12 (June, 1937), No. 6 
Typical Troubles in Modern Sound Reproducing 

Units (p. 7). L. CHADBOURNE 

Aligning the Lamp House with the Projector Mecha- 
nism (p. 19). A. C. SCHROEDER 

Journal of the Optical Society of America 

27 (July, 1937), No. 7 
Theory of Three-Color Reproduction (p. 227). C. HARDY AND 



Experimental Determination of Photographic 'Density 

(p. 241). A. KOERNER AND 



19 (June, 1937). No. 7 

Filmgerate in Osterreich (Austrian Film Apparatus) 

(p. 148). P. SCHROTT 

Die Geschichte der Bildwechselzahl (History of Image 

Frequency) (p. 153). F. P. LIESEGANG 

Die Eurocord-Tonkamera (Eurocord Sound Camera) 

(p. 155). H. FREESE 

Die Bedeutung der Normstimmung fur Musikauffiihr- 
ungen, Tonaufnahme und Tonwiedergage (The Sig- 
nificance of Standard Agreement on Musical Regis- 
tration, Sound Recording, and Sound Reproducing) 
(p. 159). O. FRANK 

Negative-Entwicklung nach Proben oder mit kon- 
stantem Gammawert? (Shall Negatives Be Developed 
According to Tests or to a Constant Gamma Value?) 
(p. 161). L. KUTZLEB 

Fortschritte der Hochfrequenzkinematographie (Prog- 
ress in High-Speed Motion Picture Photography) 
(p. 164). R. THUN 

Ein Vorbote des Plastischen Farbentonfilms (A Fore- 
runner of Stereoscopic Color Sound-Films) (p. 165). L. KUTZLEB 

Proceedings of the Institute of Radio Engineers 

25 (June, 1937), No. 6 
Television in Great Britain (p. 697). N. ASHBRIDGE 


Mein Weg mit dem Film (My Experiences with Film) : Oskar Messter, Max 

Hesse Verlag, Berlin-Schoneberg, 1936 (150 pp.). 

This book was written at the request of Oskar von Miller to form a foundation 
for the collection of historical data and apparatus that Messter gave to the Ger- 
man Museum in Munich. A short historical resume of the work of Edison, Lu- 
miere, Anschutz, the Skladanowsky brothers, and others prefaces the book. 

The name of Oskar Messter has been connected with the German motion pic- 
ture industry since its beginning, and there are very few branches to which Mess- 
ter has not contributed. 

As early as June 3, 1896, Messter built and sold his first projector. In the same 
year he built his first camera, and because he was unable to obtain film, he used 
8-exposure Kodak film which he slit to a width of 35-mm. 

After his first cameras had been built, Messter designed and built the first under- 
cut gate to protect the film from scratches. For the film movement he built a 
four-part Maltese cross instead of using the 5- and 7-part cross which had been 
used up to this time. As early as 1900 he built a working model of a projector 
using mirrors to produce an optically intermittent movement. 

In 1916 he obtained a patent on a variable shutter, and later on a camera with 
an automatic device for fades and dissolves. 

In 1896 he constructed a film perforator which perforated 120 frames per min- 
ute. For his first developing outfit he built a drum having a capacity of 60 feet 
of film, and later designed a processing machine for continuous developing, fixing, 
and washing. 

He obtained a patent in 1900 for an optical printer for trick work. To keep 
the negative and positive in good contact, air pressure was used in the gate. 

As early as 1897 he built and sold a projector using 35-mm. film which exposed 
pictures along each half of the film width. It was used for amateur and teaching 

A patent was granted to him for synchronizing a player-piano with the projec- 
tor. He employed a musical director to write music to accompany the film, and 
in 1903 started work on synchronizing a gramophone with the projector. More 
than 500 theaters were equipped by 1913 with this apparatus. 

Messter became greatly interested also in color photography, and built a camera 
with three lenses in 1898. To get slow-motion photographs he also designed a 
high-frequency camera. His first camera was capable of taking 64 frames per 
second. Later he built special cameras for Krupp for bullet photography, as well 
as cameras for recording instruments on aeroplanes. 

During the War he constructed cameras for time-lapse photography from the 
air. He also built a camera of the machine-gun type for aerial shooting practice. 

Besides these extensive activities he owned and operated a motion picture 
studio, where he made his first releases, each 18 meters in length. His first studio 
was opened in November 1896. It was independent of daylight, and used four 
arc lamps (50 amp.) for illumination. 


The actors were his friends and members of his family, and later members of 
the opera and theaters were used in the casts. While these short films were be- 
ing produced Messter worked diligently to improve his cameras and projection 

The slow evolution of the industry is carefully presented in the book with the 
aid of many pictures and diagrams. The sections dealing with early work in 
sound recording are especially interesting. This book represents a valuable con- 
tribution to the historical development of the industry, and should be read by 
those interested in the growth of the motion picture. 



of the 

(Correct to Aug. 20th; additional appointments or changes may be made at 
any time during the year as necessity or expediency may require.) 




G. FRIEDL, JR., Chairman 



J. I. CRABTREE, Chairman 



T. E. SHEA. Chairman 





J. A. BALL, Chairman 






W. C. KUNZMANN, Chairman 








A. W. SCHWALBERG, Chairman 









E. THEISEN, Chairman 







E. THEISEN, Chairman 


J. I. CRABTREE, Chairman 




E. A. WILLIFORD, Chairman 







D. E. HYNDMAN, Chairman 






R. F. MITCHELL, Chairman 






G. E. MATTHEWS, Chairman 








J. G. BRADLEY, Chairman 






[j. s. M. P. E. 


E. R. GEIB. Chairman 














R. H. RAY 












New York 








District of Columbia 

































O. F. NEU 

J. S. ClFRE 











New Zealand 

















G. D. LAL 













Sept., 1937] 







J. G. FRAYNE, Chairman 


A. N. GOLDSMITH, Chairman 


H. RUBIN, Chairman 


P. A. McGuiRE 


W. WHITMORE, Chairman 










P. A. McGuiRE 






E. K. CARVER, Chairman 


R. E. FARNHAM, Chairman 








(Atlantic Coast) 

G. FRIEDL, JR., Chairman 

L. W. DAVEE, Past- Chairman M. C. BATSEL, Manager 

D. E. HYNDMAN, Sec.-Treas. H. GRIFFIN, Manager 


C. H. STONE, Chairman 

R. F. MITCHELL, Past-Chairman O. B. DEPUE, Manager 

S. A. LUKES, Sec.-Treas. B. E. STECHBART, Manager 

(Pacific Coast) 

K. F. MORGAN, Chairman 

G. F. RACKETT, Past-Chairman J. O. AALBERG, Manager 

G. A. CHAMBERS, Sec.-Treas. H. W. MOYSE, Manager 




Officers and Committees in Charge 

W. C. KUNZMANN, Convention Vice-President 

J. I. CRABTREE, Editorial Vice-President 

S. K. WOLF, President 

O. M. GLUNT, Financial Vice-President 

G. E. MATTHEWS, Chairman, Papers Committee 

G. FRIEDL, Chairman, Atlantic Coast Section 

Local Arrangements and Reception Committee 

G. FRIEDL, JR., Chairman 






Registration and Information 

W. C. KUNZMANN, Chairman 

Ladies' Reception Committee 

MRS. S. K. WOLF and MRS. O. F. NEU, Hostesses 



Banquet Committee 

A. S. DICKINSON, Chairman 




Publicity Committee 

W. WHITMORE, Chairman 





Projection Committee 

H. GRIFFIN, Chairman 





Officers and Members of New York Projectionists Local 306, I. A. T. S. E. 

Membership Committee 

E. R. GEIB, Chairman 



Hotel Accommodations 

O. F. NEU, Chairman 




The headquarters of the Convention will be the Pennsylvania Hotel, where ex- 
cellent accommodations have been assured and a reception suite will be provided 
for the Ladies' Committee. An excellent program of entertainment will be ar- 
ranged by the hostesses. 

Special hotel rates guaranteed to SMPE delegates, European plan, will be 
as follows: 

One person, room and bath $3 . 50 

Two persons, double bed and bath 5.00 

Two persons, twin beds and bath 6 . 00 

Parlor suite, one person 11 .00 up 

Parlor suite, two persons 13.00 up 

Room reservation cards will be mailed to the membership of the Society in the 
near future, and everyone who plans to attend the Convention should return his 
card to the Hotel promptly in order to be assured of satisfactory accommodations. 
Consult your local railroad ticket agent with regard to coach and pullman rates. 

Parking accommodations will be available to those who motor to the Conven- 
tion at the fire-proof garage of the Hotel, at the rate of $1 .25 for twenty-four hours 
or $1.00 for twelve hours, including pick-up and delivery at the door of the Hotel; 
weekly rate, $7.50. 

Technical Sessions 

An attractive program of technical papers and presentations is being arranged 
by the Papers Committee. All technical sessions, apparatus symposiums, and 
film programs will be held in the Salle Moderne of the Hotel, on the eighteenth 

There will be no general Apparatus Exhibit, but those who have developed new 
equipment during the past year are invited to submit technical descriptions of it 
to the Papers Committee for possible inclusion in the Apparatus Symposium. 

Sept., 1937] FALL CONVENTION 341 


Registration headquarters will be located on the eighteenth floor of the Hotel at 
the entrance of the Salle Moderne, where the technical sessions will be held. Ex- 
press elevators from the lobby will be reserved for the Convention. All members 
and guests attending the Convention are expected to register and receive their 
badges and identification cards required for admission to certain evening sessions 
of the Convention, as well as to various de luxe motion picture theaters that will 
honor the cards as courtesy admissions. 

Luncheon and Banquet 

The usual informal get-together luncheon will be held at noon on October llth 
in the Roof Garden of the Hotel, and the semi-annual banquet and dance will 
take place on the evening of October 13th. 

Addresses will be delivered by prominent members of the industry on both 
occasions. At the banquet the annual presentation of the SMPE Progress Medal 
and the Journal Award will be made, and the officers-elect for 1938 will be intro- 
duced. The banquet will conclude with dancing and entertainment. 

Tickets for admission to the informal luncheon and the banquet may be ob- 
tained at the registration desk. Banquet tables reserved for 8, 10, and 12 per- 

Ladies' Program 

An especially attractive program for the ladies attending the Convention is 
being arranged by Mrs. S. K. Wolf and Mrs. O. F. Neu, Hostesses, and the Ladies' 

A suite will be provided at the Hotel, where the ladies will register and meet for 
the various events on their program. Further details will be published in a suc- 
ceeding issue of the JOURNAL. 

Entertainment and Diversion 

Golfing privileges may be arranged at several country clubs in the vicinity of 
New York, as well as various tours to points of interest in and about the city. 
These arrangements may be made either at the Convention registration desk or 
through the management of the Hotel. 

Points of Interest 

Headquarters and important branch offices of practically all the important firms 
engaged in producing, processing, and exhibiting motion pictures and in manu- 
facturing equipment therefor, are located in metropolitan New York. Although 
no special trips or tours have been arranged to any of these plants, the Conven- 
tion provides opportunity for delegates to visit those establishments to which they 
have entree. Among the points of interest to the general sightseer in New York 
may be listed the following : 

Metropolitan Museum of Art. Fifth Ave. at 82nd St.; open 10 A.M. to 5 P.M. 
One of the finest museums in the world, embracing practically all the arts. 

American Museum of Natural History.- 72nd St. between Columbus Ave. and 
Central Park West; 9 A.M. to 5 P.M. 


New York Museum of Science and Industry. RCA Building, Rockefeller Cen- 
ter; 10 A.M. to 5 P.M. Exhibits illustrate the development of basic industries, 
arranged in divisions under the headings food, industries, clothing, transportation, 
communications, etc. 

Museum of the American Indian. Broadway and 155th St., 2 P.M. to 5 P.M. 

Hayden Planetarium. Central Park West at 77th St. Performances at 1 1 A.M., 
2 P.M., 3 P.M., 4 P.M., 8 P.M., and 9 P.M. Each presentation lasts about 
45 minutes and is accompanied by a lecture on astronomy. 

Rockefeller Center. 49th to 51st Sts., between 5th and 6th Aves. A group of 
buildings including Radio City Music Hall, the Center Theater, the RCA Building, 
and the headquarters of the National Broadcasting Company, in addition to 
other interesting general and architectural features. 

Empire State Building. The tallest building in the world, 102 stories or 1250 
feet high. Fifth Ave. at 34th St. A visit to the tower at the top of the building 
affords a magnificient view of the entire metropolitan area. 

Central Park. 59th to 110th Sts., Central Park West to Fifth Ave. Here are 
located the Metropolitan Museum of Art, and a number of other general and 
educational features including the zoological garden and "Cleopatra's Needle." 
The latter is an Eyptian obelisk presented to the City in 1879 by the Khedive of 

Greenwich Village. New York's Bohemia; a study in contrasts. Here are 
located artists and artisans, some of the finest homes and apartments, and some 
of the poorest tenements. 

Holland Tunnel. The first vehicular tunnel constructed beneath the Hudson 
River; at Canal St., connecting New York with New Jersey; more than 9000 
feet long. 

Foreign Districts. Certain sections of the city are inhabited by large groups of 
foreign-born peoples. There is the Spanish section, north of Central Park; the 
Italian district near Greenwich Village; Harlem, practically a city in itself, num- 
bering 300,000 negroes; Chinatown, in downtown Manhattan; the Ghetto, the 
Jewish district; and several other such sections. 

Miscellaneous. Many other points of interest might be cited, but space permits 
only mentioning their names. Directions for visiting these places may be obtained 
at the Convention registration desk: Pennsylvania Station, Madison Square, 
Union Square, City Hall, Aquarium and Bowling Green, Battery Park, Washing- 
ton Square, Riverside Drive, Park Avenue, Fifth Avenue shopping district, Grand 
Central Station, Bronx Zoo, St. Patrick's Cathedral, St. Paul's Chapel, Cathedral 
of St. John the Divine, Trinity Church, Little Church Around the Corner, Wall 
St. and the financial district, Museum of Natural History, Columbia University, 
New York University, George Washington Bridge, Brooklyn Bridge, Triborough 
Bridge, and Statue of Liberty. 

Steamships. The S. S. Normandie will be in dock open for inspection, on Octo- 
ber 12th, pier 88 at the foot of West 48th St.: tickets on sale at the pier. 50tf each. 



On or about September 1st, ballots will be mailed to the Fellows and Active 
members of the Society for voting for Officers for 1938. The nominees are as 
follows : 

K. F. Morgan, Executive Vice-P resident 

L. A. Jones, Engineering V ice-President 

E. A. Williford, Financial Vice-President 

J. Frank, Jr., Secretary 

L. W. Davee, Treasurer 

H. Griffin, Governor 

A. S. Dickinson, Governor 

A. C. Hardy, Governor 

G. F. Rackett, Governor 

W. A. Mueller, Governor 

R. E. Farnham, Governor 

Three of the six nominees for Governor are to be elected. The executive vice- 
president, the secretary, and the treasurer are elected for one-year terms; the 
other officers and governors for two-year terms. 

The ballots will be counted on the opening day of the Fall Convention at New 
York (October llth), and announcement of the results will be made immediately. 
The officers-elect will be presented at the semi-annual banquet on October 13th, 
and will assume office on January 1st. 

The remaining officers and governors, named below, continue in office until 
December 31, 1938: 

S. K. Wolf, President 

H. G. Tasker, Past-President 

J. I. Crabtree, Editorial Vice-President 

W. C. Kunzman, Convention Vice-President 

M. C. Batsel, Governor 

A. N. Goldsmith, Governor 


An exhibition of cinematography, comprising films, stills, and apparatus will be 
held at the galleries of the Royal Photographic Society at 35 Russell Square, 
London, W.C.I, November 13-27, 1937. 

The keynote of the exhibition will be "The Film as a Social Force." During its 
course, lectures and demonstrations of interest to both professionals and amateurs 
will be given. 




[J. s. M. p. E. 

A competition, embracing films of all types, has been arranged, the rules and 
entry form for which may be obtained by writing to the secretary of the Society 
at the above-given address. A selection from the films receiving awards will be 
shown during the exhibition. 


At a recent meeting of the Admissions Committee, at the General Office of the 
Society, the following applicants for membership were admitted to the Associate 


Chemical & Research Corp., 
9308 Santa Monica Blvd., 
Beverly Hills, Calif. 
4151 N. Mozart St., 

Chicago, 111. 
2125V2 Ridge Ave., 

Evanston, 111. 
2216 Lunt Ave., 

Chicago, 111. 
Ill Chestnut St., 
Audubon, N. J. 

DlSciULLO, H. 

144 Westville St., 

Dorchester, Mass. 
3426 W. Olympic Blvd., 

Los Angeles, Calif. 
3601 44th Ave., South 
Minneapolis, Minn. 
HALL, T. O. 

Hall & Connolly, Inc., 
24 Van Dam St., 
New York, N. Y. 


512 Clark St., 

South Orange, N. J. 
JUST, J. J., JR. 
5329 School St., 

Chicago, 111. 
Wilhelmstr. 9, 
Berlin, Germany. 

1434 School St., 

Chicago, 111. 

Seattle Lighting Dept., 
City Light Bldg., 
Seattle, Wash. 
308 W. 94th St., 

New York, N. Y. 
577 Floral Drive, 
Whittier, Calif. 

4520 N. Damen Ave., 
Chicago, 111. 


779 Simpson Ave., 

Salt Lake City, Utah. 

The Gramophone Co., Ltd., 
Post Box No. 118, Fort 
Bombay, India. 
PEEK, J. E. 

708 W. Grand Ave., 
Oklahoma, Okla. 
2838 S. Gaffey St., 
San Pedro, Calif. 
4411 Regent St., 
Duluth, Minn. 

Heyer-Schultz, Inc., 
39 Orange Road, 
Montclair, N. J. 
3130 S. Karlov Ave., 
Chicago, 111. 

Sept., 1937] 




1584 W. Washington Blvd., 

Los Angeles, Calif. 

467 Central Park West, 

New York, N. Y. 

329 Washington Ave., 

Wilmette, 111. 

4254 N. Mozart St., 
Chicago, 111. 


2319 Doughlass St., 

Brooklyn, N. Y. 

68, Kensington Mansions, 
Earls Court, London, S.W. 5. 

Cummings & Wilson, 
29 Alberta St., 
Sydney, Australia. 

In addition, the following applicants have been admitted by vote of the Board 
of Governors to the Active grade: 


7063 Lancewood Ave., 

Hollywood, Calif. 
815 Riverside Drive, 
New York, N. Y. 
27 W. 72d St., 
New York, N. Y. 


Electrical Research 
Products, Inc., 
250 W. 57th St., 
New York, N. Y. 


117 Beach 59th St., 
Arverne, L. I. 

Cameramen on loca- 
tion in the desert near 
Yuma, Arizona, are 
working under diffi- 
culties in shooting 
this scene from the 
Technicolor produc- 
tion, "The Garden of 
Allah." Marlene Dietrich and 
CharlesBoyer co-star in this David 
O. Selznick production, under the 
direction of Richard Boleslawski. 
Rosson, Photographic adviser; W. 
A. Oettel, Studio Chief Electrician 

Exceptional penetration and carrying power are required of 
light source to pierce the obscuring clouds of a sand stoi 
on the desert, but the carbon arc proved equal to the task 


> required of a H 
a sand storm H 

I tr> the task. iH 

It is silenf, cool ond remarkably fait. 

It has the photographic qualities of daylight. 

It has proved a necessity for color productions 

It Improves black and white photography. 



Umt of Union CarkiJ (TJlj^ and Carbon Corpo.ation 





Volume XXIX OCTOBER, 1937 Number 4 



How Motion Pictures Are Made A Symposium of the Spring, 

1937, Convention, Held at the Universal Studios 349 

Preparing a Story for Production ROBERT PRESNELL 350 

Prescoring for Song Sequences BERNARD BROWN 356 

Set Design from Script to Stage JOHN HARKRIDER 358 

Handling Lighting Equipment in Production . FRANK GRAVES 360 

Film Editing MAURICE PIVAR 363 

Setting Music to Pictures CHARLES PREVIN 372 

Assembling a Final Sound-Track EDWIN WETZEL 374 

Report of the Sub-Committee on Perforation Standards 376 

A New Dynamic Light- Valve E. GERLACH 388 

Color Stills O. O. CECCARINI 397 

Mathematical Relations between Grain, Background Noise, and 

Characteristic Curve of Sound-Film Emulsions 


New Motion Picture Apparatus: 

Laboratory Equipment for the Smaller Laboratory 

A. REEVES 446 

Current Literature 455 

Fall Convention : Hotel Pennsylvania, New York, N. Y., Octo- 
ber 11-14, 1937 

General Information 457 

Tentative Program 461 

Society Announcements 466 





Board of Editors 
J. I. CRABTREE, Chairman 



Subscription to non-members, $8.00 per annum; to members, $5.00 per annum, 
included in their annual membership dues; single copies, $1.00. A discount 
on subscriptions or single copies of 15 per cent is allowed to accredited agencies. 
Order from the Society of Motion Picture Engineers, Inc., 20th and Northampton 
Sts., Easton, Pa., or Hotel Pennsylvania, New York, N. Y. 
Published monthly at Easton, Pa., by the Society of Motion Picture Engineers. 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General and Editorial Office, Hotel Pennsylvania, New York, N. Y. 

West-Coast Office, Suite 226, Equitable Bldg., Hollywood, Calif. 
Entered as second class matter January 15, 1930, at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. Copyrighted, 1937, by the Society of 
Motion Picture Engineers, Inc. 

Papers appearing in this Journal may be reprinted, abstracted, or abridged 
provided credit is given to the Journal of the Society of Motion Picture Engineers 
and to the author, or authors, of the papers in question. Exact reference as to 
the volume, number, and page of the Journal must be given. The Society is 
not responsible for statements made by authors. 


President: S. K. WOLF, 100 E. 42nd St., New York, N. Y. 
Past-President: H. G. TASKER, Universal City, Calif. 

Executive Vice-President, G. F. RACKETT, 823 N. Seward St., Hollywood, Calif. 
Engineering Vice-President: L. A. JONES, Kodak Park, Rochester, N. Y. 
Editorial Vice-President: J. I. CRABTREE, Kodak Park, Rochester, N. Y. 
Financial Vice-President: O. M. GLUNT, 180 Varick St., New York, N. Y. 
Convention V ice-President: W. C. KUNZMANN, Box 6087, Cleveland, Ohio. 
Secretary: J. FRANK, JR., 90 Gold St., New York, N. Y. 
Treasurer: L. W. DAVEE, 250 W. 57th St., New York, N. Y. 


M. C. BATSEL, Front and Market Sts., Camden, N. J. 

A. S. DICKINSON, 28 W. 44th St., New York, N. Y. 

G. FRIEDL, JR., 25 Hunter Ave., Fanwood, N. J. 

A. N. GOLDSMITH, 444 Madison Ave., New York, N. Y. 

H. GRIFFIN, 90 Gold St., New York, N. Y. 

A. C. HARDY, Massachusetts Institute of Technology, Cambridge, Mass. 

K. F. MORGAN, 7046 Hollywood Blvd., Los Angeles, Calif. 

C. H. STONE, 205 W. Wacker Drive, Chicago, 111.- 




MAY 25, 1937 

As one of the events of the Spring, 1937, Convention of the Society held at Holly- 
wood, Calif., a symposium on the subject of "How Motion Pictures Are Made" was 
arranged by members of the staff of Universal Studios, Mr. H. G. Tasker* acting 
as Chairman. The audience of members and guests of the Society, numbering in 
excess of 600 persons, assembled at 8 P.M. on stage 10 of the Studio, which is normally 
devoted to scoring and prescoring. 

MR. H. G. TASKER :* Ladies and gentlemen, I am sorry to announce 
that Mr. Chas. R. Rogers, Executive Producer and Vice- President of 
Universal Pictures, is unable to be here tonight to welcome you as he 
had planned to do. We are most fortunate, however, that he has 
sent, to represent him, not only a most able assistant, but also a man 
whom we at Universal regard most highly. I am happy to introduce 
to you our Studio Manager, Mr. Val Paul. 

MR. VAL PAUL : It is hardly necessary to make a speech of wel- 
come, because I want every member of your Society to feel at any 
time that you are here, and particularly at this time, that the gates 
and doors of Universal City are always open to you. I hope you 
will take advantage of that so that we may serve as your host at any 
time the Society may happen to meet in our fair city. 

Nevertheless, I deem it a pleasure to speak before you, whom I 
might term the unsung heroes of the motion picture industry. I say 
that because I feel that most of you gentlemen who are connected 
with the Society are never seen or never heard; yet through your 
efforts you have made it possible for millions to see and hear their 
favorites on the screen. 

I thank you all for coming here, and I certainly hope that you will 
enjoy the program that the boys have prepared for you. 

MR. TASKER : We have an interesting program for you this even- 
ing, one by which we hope to aid in a very small but perhaps impor- 

*Chief Sound Engineer, Universal Pictures Corp., Universal City, Calif. 




tant way the men who are working in the industry, by giving you a 
little more intimate view into the way motion pictures are produced 
than is ordinarily available. Sometimes even those of us who are 
immersed in studio work do not have a very good chance to see how 

Left to right: (Standing) Edwin Wetzel, Dubbing Mixer; Charles Previn. 
Musical Director; (seated) Maurice Pivar, Supervising Editor; Bernard 
Brown, Chief Mixer; Homer Tasker, Sound Director. 

our colleagues in the other departments work, and I confess that I have 
been looking forward to this evening with some pleasure in the hope 
of learning from Mr. Presnell and Mr. Harkrider and Mr. Graves, 
and from each of the other men on the program tonight, some things 
about the way their work is done of which I had no inkling before. 
The first of our speakers this evening is a man who is responsible 
for getting a picture started and for carrying it through to a success- 
ful conclusion; upon whose shoulders rests the responsibility of pro- 
duction. I am happy to introduce Mr. Robert Presnell, associate 
producer at Universal. 



There is an old saying among us in the motion picture industry 
that every picture is grief and that is the way it starts. 

*Associate Producer, Universal Pictures Corp., Universal City, Calif. 


When you see a picture in the theater and it rolls out smoothly in 
front of your eyes you probably have no idea of what has gone into the 
making of that picture before it arrives in the hands of you engineers 
and technicians, so we shall start at the beginning. 

Assume that a story is purchased. How it is purchased is another 
story of grief, but it does not enter into this picture. Together with 
a number of other stories it is sent around to the producers on the lot, 
who read the stories. Here is what they have to think about when 
they read those stories: 

Suppose you have to make four of the lower-budget pictures, and 
you know that each of them is to cost the nominal sum of $125,000 to 
$150,000, and no more. You must not exceed that, because that is 
all you will get. The first problem that comes up when you read one 
of the stories is, can it be made for that amount of money ? Of course, 
you may have to take out this bit of story; put something there 
that is a little different; or down there something that we have in 
stock; but that will be all right. Suppose you decide that perhaps 
the story is all right as far as the number and cost of sets are con- 
cerned, so you will seriously consider producing it. 

Now, the next thing is to find out whom you can get to play the 
leading part. All right; there are Joe Dokes and Henry Smith and 
Bill Brown ; but Joe Dokes costs you $25,000 a picture, so you can 
not use him. Bill Brown costs $20,000, and there is a big accumula- 
tion* on Henry Smith. You would like to use him, but the big ac- 
cumulation, say, $15,000, would have to be taken up, so you can not 
use him. Finally you simmer it down to some personality on the 
lot, some young fellow who is just starting out. Perhaps he needs a 
chance to do bigger things. He fits into the part and you know that 
you can get him for $5000 for this picture and then perhaps you 
will try to see whether you can make a star of him. So after fooling 
about a bit you finally decide to use him. 

Then you realize that because your final picture has to cost less 
money than other types of pictures you have no well known personality 
in it, and that, as a result, you have a box-office handicap. 

That is not true of the higher-budget pictures, because there you 
start out with your stars already cut out for you the big names, and 

"This is the amount of salary of a player who is on contract that has been paid 
to him since his last picture and which is usually charged to the cost of his next 


then you can "go to town." It is no problem then; it is the little 
pictures that are difficult. 

Having no box-office appeal in the personalities because you are 
taking young, new actors not very well known, and are going to 
try to make stars of them, what have you got to sell? You have to 
sell the story angle, something that is fresh and new, presented in a 
fresh way, that will attract people to the picture and make them like 
it; something that is catchy and has something in it that will move 
along, and that they will enjoy. That is the first thing you must 
plan to sell as you read the story. 

Next you have to decide upon the story strength itself, what its 
situations are, how strong it is, and how logical. Finally you do de- 
cide that it will make a pretty good story, but you realize that you 
will have to change this and that, and instead of the man biting the 
girl, the girl will have to bite the man, and so forth and so on. Finally 
you drop a note to Mr. Rogers, telling him that you would like to 
try this story, that you see a fresh angle in it, and think that you can 
do it within the money allowance. Perhaps the next morning you 
find a note on your desk, telling you that it is "in your lap," and you 
have got it. 

The next thing you do is to call in the scenario head. You need 
a writer to start putting the story into producible form. Now we 
are in a new phase of the production. You have already had a few 
headaches to start with, but here are some new ones. You want a 
writer, and look through the list of available writers in Hollywood. 

Now, as in any other business, the good writers are all pretty well 
tied up in other places when you want them. You have to find some- 
body who you know can write that story the way you want it, and 
who does not get more money than you feel you can allow. Writers 
get all the way from $150 to $3500 or $4000 a week. I have always 
said that it is better economy to use a good writer, no matter what 
you have to pay, and use him for less time, than it is to use a poor 
writer and spread the work over many, many weeks, because you 
will always get into trouble by doing so. 

So you go through the list of available writers. There are not too 
many writers here in Hollywood not as many as you think. There 
are probably about four or five hundred writers doing business in 
Hollywood, and about 100 of them, or less, do all the actual work; so 
out of the 85 or 100 you have to pick one who can do the story within 
all the limitations that are beginning to hedge about you. Finally 


you decide upon Willie Smith. He is a good writer, so you engage 
him. You talk to him, and tell him the story, and let him read it. 
He comes in the next day; perhaps he is enthusiastic about the pic- 
ture. He has a new angle on it, which he wants to try. You give 
him the job, and he starts to work. You tell him further that this is 
a picture that has to be done, let us say, in 18 shooting days. You 
have to shoot it within 18 days because it is costing you from $3000 
to $5000 a day to shoot the picture, so if you run over that you will 
run over your budget; furthermore, if you are going to shoot the 
picture in 18 days, you should not have more than 18 sets in the pic- 
ture. You do not want a lot of costly moving about, but what you 
do want is to be able to shoot in any one set for a full day at least. It 
is much more economical to do it that way. So the writer starts to 
write the picture, keeping in mind the charges and keeping the sets 
down to a minimum. 

In this kind of picture, we always try to say something. It must 
be about something. Most of the pictures have headlines, things 
that sell themselves; things of general interest, which carry the in- 
terest as the story is told through the characteristics of people who 
move and breathe and do things. 

Finally, in a picture of this kind, after about four or five weeks, 
you get your first draft. The first draft is your springboard, as we 
say in the motion picture industry, out of which your story is built. 

Now you have got something tangible in your hand, and can weigh 
it. It should be about 100 or 105 pages long in order to get about 
6000 feet of finished film, which is what you want; you know exactly 
the number of sets required, and in order not to run over the schedule 
you want to be sure that there are no sets in the script that cannot be 
produced in the length of time set. 

With the first draft, you go into the first conference with your 
writer and the head of your story board if you have one and in this 
case we usually go to Mr. Val Paul. He reads the story and says 
it is wrong here or it is wrong there ; and so with the writer and Mr. 
Paul you straighten out all the questionable points, cut out all the 
dead spots, and so forth, so that the story moves quickly, rapidly, 
and amusingly, right straight through. You cut out all the long 
walks down hallways and things of that sort; you seem to jump from 
one scene into another scene so that the whole moves right along, 
each scene building higher and higher as the story progresses. 

After the conference you are ready for your second draft, and then 


you call in your director to read the story. The director wants some 
changes; he has certain problems to bring up; he wonders whether 
or not this scene can be done; something has to be done here, and 
something has to be done there; so a little more of the grief comes in 
with the director, who also adds to the cost of the picture. You 
have to engage a director who will not cost too much, or there 
will be an over-balance again. You have to maintain your balance 
all the way through. 

Finally the director has had his say, and an assistant director is 
assigned to him and a cutter is put on the picture. You go into the 
final draft, making all the changes agreed upon, and finally get out 
the final draft, and it is satisfactory. Before that happens, how- 
ever, the first draft goes to Mr. Murphy, head of the production 
department, who sometimes holds it up and sometimes says it is 
all right. 

Production department problems are a little different. The 
script is read and estimating begins. Every scene in the script must 
be estimated, how many persons are in it, what it will cost to build 
each set, what the wardrobe will cost, what the lighting will cost, and 
what the sound will cost. Everything that goes into the cost of a 
scene is figured, and the sum of all the estimates for each scene con- 
stitutes your budget. Sometimes the estimate is high, and some- 
times it is very close to your aim; but sometimes you find it impos- 
sible to do the picture with the money allowed, and then you have to 
do some re-vamping, some more cutting down and changing to bring 
the cost within your limits. Finally you get it within those limits, 
and then the art department goes to work. Blueprints are made of 
the sets and so forth Mr. Harkrider will tell you what is done in 
that department. You choose a title for the picture, and then you 
are almost ready to start. Your director and assistant director are 
ready, and the cameraman and the whole crew have been assigned 
and are "ready to go." 

Now comes the casting. The casting director and associate 
producer sit down to argue the problem ; and when four or five per- 
sons in a room are asked their opinions of something, you may ex- 
pect to get four or five different opinions. That usually happens in 
the casting, at least, for the smaller parts. The big parts are pretty 
well settled, as you have had them in mind from the very beginning. 
As to the smaller parts, you talk it over and you find out whether 
this one or that one will do ; then you have to find out whether they 


are available, whether they are under contract either to you or to 
another studio, or whether they are busy at another picture 
elsewhere. If they are busy, you have to get some one else. If you do 
borrow an actor from another studio you pay somewhat more 
than you do for your own people. You have to pay what is called 
the "three-and-f our- weeks," that is, pay four weeks' salary for three 
weeks' work. All this affects your budget, and again you have to 
find actors who are adequate to play the parts at prices within your 
range, and you have to reach out and get them wherever you can in 
the industry. Sometimes it is very difficult, and sometimes you have 
to juggle your schedules so that the work will continue right through 
without your having to carry the actors along for too long a time. 
There is a rule in Hollywood that if you start with a character in a 
picture if he has started, say, on the second day of the picture, and 
his next scene does not come until the sixteenth day of the picture, 
you have to pay him from the second day right through to the six- 
teenth. It used to be in the old days that you might be able to make 
a deal with him and pay him for the two days' work; but not any- 
more. . For that reason the schedules have to be rearranged in such 
a way that all actors (except your own contract players) run through 
their scenes almost consecutively. Sometimes it is necessary to 
carry actors for a day or two, but if it is more than that, it runs into 
a lot of money. 

Finally the casting is done ; you sit down with a sigh of relief, and 
your picture is ready to start the next morning. When the fateful 
morning comes, you go down to your first set, shake everybody's hand, 
and then get off the set very quickly. Now your grief really begins. 

MR. TASKER : Although Mr. Presnell has taken us from the point 
of choosing the story material clear up to the start of production, 
there are two steps that we shall discuss further this evening. One 
of these, already mentioned, is the work of the art department, which 
will be described in a few minutes. The other occurs whenever there 
are to be songs or musical numbers in a picture, and since it comprises 
making some of the music for the picture before any shooting begins, 
it is called "prescoring." Mr. Bernard Brown, the head of our music 
and effects department, will describe and demonstrate prescoring 
for sound sequences. 




As most of you know, we do not record songs or orchestras on the 
set during the filming of a picture. Instead, we record them in ad- 
vance, usually before the picture goes into production. This we 
call prescoring. We prescore for several reasons, which I shall ex- 
plain as I outline the method of prescoring. 

To record a vocal selection with orchestral accompaniment we 
bring the soloist and the orchestra to this stage, which has been built 
for music recording. We are able to do much better musical record- 
ing here than on the sound stages, partly because we can use micro- 
phones close to the different sections of the orchestra. That could 
not be done if the orchestra were photographed at the time of record- 
ing because the microphones would show in the picture. 

First, we rehearse the orchestra alone, to check the arrangement 
and to see that there are no mistakes in the music Then, the soloist 
rehearses with the orchestra, showing the musical director and the 
orchestra exactly how she would like the accompaniment played. 

Next we record the orchestra alone, the soloist mouthing the words 
silently and the musical director following her and directing the 
orchestra accordingly. If this is a good "take" the orchestra is dis- 

This procedure is very economical, as we finish with the musicians 
in one-half the time that used to be required to record both voice 
and orchestra at the same time, making take after take and finally 
being forced to use one of the last takes made when the soloist was 

Now we have an ideal set-up for the soloist. The orchestra has 
gone, and no one is allowed upon the stage who is not actually working 
on the recording. 

Next we play back the orchestral record we have just made, us- 
ing head-phones to listen to it. 

As you notice, the soloist has only one earphone, so that she is able 
to hear the music played back with one ear and her own voice with 
the other. The music is played at a fairly low level so that our soloist 
can hear clearly every note she sings without its being covered by 
the orchestra. In order to pronounce her words clearly and get the 

* Chief Music and Dubbing Mixer, Universal Pictures Corp., Universal City 


proper tone placement in her throat it is sometimes necessary for 
the singer to make peculiar faces, which she can do without em- 
barrassment as she is among friends and is not being photographed. 
In recording the songs it is not necessary to make many takes, 
as we are able to take the best parts of two or three takes and assem- 
ble them into one good take, which saves a lot of time in addition to 
the soloist's voice. When this assembly has been done, we make a 
combined record of voice and orchestra which we use as a playback 
on the set when photographing the scene in which the soloist is sup- 
posed to sing the song. Photographing a scene with playback is done 
as follows : The record of the song is placed upon a reproducing ma- 
chine which is interlocked with the camera so that the camera and 
the playback run at the same speed. As the camera turns and photo- 
graphs the actor, the record is reproduced over a loud speaker and 
the singer mouths the words of the song again, either silently or other- 
wise, without having to make the excessive facial contortions re- 
quired for tone placement and enunciation. Here is where the pre- 
scoring is very helpful to the singer, because she can now think about 
the scene and look her best, without having to worry about the qual- 
ity of her singing. 

At the conclusion of Mr. Brown's paper, Miss Deanna Durbin was introduced to 
the audience and sang" Sunbeams" from the Universal Picture "One Hundred Men and 
a Girl," then in production. Head-phones had been wired throughout the audience so 
that the spectators could listen to the orchestral playback as Miss Durbin sang her song 
for the recording. 

This prescored recording was later to be dubbed into the picture photographed on 
the production stage as described below. 

MR. TASKER: Although designing the sets for a motion picture 
begins as soon as, if not sooner than, the prescoring, we prefer to 
make it follow the prescoring on this program in order to show 
the logical unfolding of a set creation from script to stage. In illus- 
tration of this subject the art deparment will present drawings and 
models of the very set in which later portions of this evening's pro- 
gram will take place. Through the courtesy of Mr. John Harkrider, 
supervising art director at Universal, the next paper will be pre- 
sented by Mr. Michael Fitzmaurice, whom you have no doubt seen 
in a number of Universal pictures. 




It is my purpose this evening to paint a word picture of New Uni- 
versal's art department; to show you how it works and functions; 
to give you, somehow, the feeling that pulsates through the members 
of its entire staff. 

First, I usher you into a long, low, white building. Youth and 
activity sound the keynote of the outer office the apprentice room. 

Herein is a story : We of the New Universal art department sin- 
cerely believe in the ambition and creative ability of youth, yet real- 
ize that every youth lacks experience and form. We give them the 
chance to acquire experience and form, by selecting a number of 
promising young men and training them, and giving them construc- 
tive criticism individually. Later, if they show the proper develop- 
ment, and many of them do, they are given positions on the staff. 
The talent so discovered and to be discovered is inestimable. 

We pass into the inner office where the art director and his asso- 
ciates work. To give you an idea of their work I shall explain how 
the department functions from the time it receives a script to the 
time a set is struck. 

The scenario department turns the script over to the art depart- 
ment. The art director and his associates carefully study it to de- 
termine the types of sets that are to be used. The artists then be- 
gin to prepare sketches keyed to the particular plot and mood of the 
story. Each scene must be visualized in its entirety. The sketch 
artists must be very versatile, and must be able to design anything from 
a small object, like a mantle piece, to a complete set. His sketches 
must show both the artistic and the mechanical side of the set. After 
the various designs are finished the art director chooses the best one 
or two or incorporates the best features of several sketches into one 
he thinks suitable. 

The art director then holds conferences with the producer, the 
director of the picture, and all the others involved, and details of 
the picture are established. 

The sketch that has been chosen is then turned over to the drafts- 
man, who works directly from the sketch. The draftsman tells the 
unit man the stock units incorporated in the set. If possible, the 

* Supervising Art Director, Universal Pictures Corp., Universal City, Calif. 


sketches include material and old sets already on the lot, which is a 
great help economically. Their use is never noticed, and the beauty 
or artistic value of the new set is never sacrificed. The unit man 
checks the stock units, and then the draftsman prepares the plan. 

After the plan is prepared a blueprint is made, which is sent to the 
estimator for a prelimary estimate. The positive print is made for a 
brown line print. This brown line print is sent to the creative plan 
model department. The creative plan model department is of ex- 
treme value from both an artistic and pecuniary standpoint. 

A model of the set is prepared, which, when finished, is taken to a 
conference of the producer, the director, the art director, and others. 
It is at this meeting that the true value of these models is brought 
out. The director can plot angles on them and plan the action. 
Electricians can figure their lighting problems. Everyone concerned 
can visualize the problems confronting him, and the models result 
in a great saving in the cost of building useless sets. Every problem 
is presented clearly. 

When the model has been accepted final blueprints are made of 
the set, which are submitted to the technical department. Con- 
struction of the set then begins. A unit man is present to see that 
the specifications of the plans are followed. Skilled carpenters and 
technicians work on the sets. If anything is added to the set during 
the construction the unit man takes care of all the details. 

When the set is constructed it is turned over to the property de- 
partment. The set is dressed by a set dresser, and the unit man sees 
that the art department's plans are carried out. This is a very com- 
plicated job, and everything must be placed correctly. Anything 
amiss would ruin the effect as a composite picture. 

The set is prepared and dressed twenty-four hours before shooting 
time. The art director approves the set and then shows it to the 
director, the cameraman, and others involved. 

The art department also designs the costumes and appurtenances 
worn by the players in the picture. It also works in close collabora- 
tion with the wardrobe department to see that their ideas are com- 
pletely carried out. The costumes are designed to harmonize with 
the sets. They are also correct as to period and seem part of the 
picture. These correct costumes also help the players psychologically 
for they feel at home in the correct attire and atmosphere. 

A set is always built using all the natural colors involved in the 
real scene whether it be Technicolor film or not, the first and most 


important reason being that the colors impart the correct atmosphere 
from the aesthetic, logical, and psychological standpoints. Second, 
the highly sensitized film of today picks up the true values of the 

The art department maintains its own research organization, 
the function of which is primarily to provide material for the sketch- 
artists to help them with their ideas and to insure the authenticity 
of their drawings. The researcher must be generally familiar with 
practically all subjects, such as the periods of interiors, exteriors, 
furniture, costumes, fashions, and so forth, so that when a call comes 
for a modern Georgian interior, for example, the research department 
will know immediately where to find it with the least possible delay. 
Such subjects as animals, paintings, costumes, details, fashions, in- 
teriors, exteriors, flowers, transportation, etc., are systematically 
indexed, so that even the matter of finding material in current and 
back issues of magazines can be accomplished with comparatively 
little loss of time. 

During the presentation of Mr. Harkrider's paper, Mr. Jack Smith, with easel, 
paper, and crayon, demonstrated the manner of preparing the sketch of a set. At 
the same time, Mr. Addison Hare, also of the Universal art department, indicated 
the manner of preparing the corresponding plans of the set. A model of the set was 
displayed, taken apart, and put together again by Mr. Paolo Grieco. 

Following the proceedings thus far described, the members and guests of the Society 
adjourned to Universal 's production stage 14, where they were shown the very set 
from "Cm Hundred Men and a Girl" that has been described above. The set was com- 
pletely dressed and lighted in the usual way with all the necessary equipment, and 
was attended by a complete personnel for shooting the scene. Miss Deanna Durbin 
and Mr. Mischa Auer, actors in the scene, were present and ready to go through 
their parts. The scene was to be photographed while Miss Durbin played her part 
singing the song that had already been prescored. 

MR. TASKER: We shall now go ahead with the next part of our 
program. Mr. Frank Graves, superintendent of the electrical de- 
partment, will discuss the production part of handling the equipment 
and how it works. 



The function of "setting up" a set with lighting equipment does 
not by any stretch of the imagination come under the heading of 

* Superintendent, Electrical Department, Universal Pictures Corp., Universal 
City, Calif. 


artistic endeavor. It consists mainly in placing an abundance of 
assorted kinds of equipment in suitable locations around and about 
the set, so that when the cameraman is called upon to light a series 
of camera set-ups, each of which is a separate problem, he has close 
at hand and, as nearly as it is possible for him to foretell, the kinds of 
lamps required in the proper places to light the particular shot. 

Sets could be arranged with much less equipment than it is the 
general practice to use, but the saving of time accomplished by not 
having to move lamps about on the platforms more than compensates 
for the cost of using the additional equipment. 

Very seldom, except when making extremely long shots on very 
large sets, are all the lamps on the set used for any one shot. As an 
example, a set that was shot a few days ago had a connected load 
of approximately 4000 amperes. Meter readings showed that the 
largest operating load was 2100 amperes and the average about 900 
amperes. The difference between the connected or "paper" load, 
as we call it, and the operating load is allowed for in our calculations, 
and we have often carried, on generators having a capacity of 18,000 
amperes, a "paper" load of 50,000 to 60,000 amperes, without trouble 
or worry. 

A large part of the labor of arranging a set is in the cabling, since 
it is necessary, of course, that all the lamps be fed and controlled. 
The usual practice is to run main feeders from a spider or bus attached 
to the runs from the power house, bring these main feeders to con- 
veniently located switchboards, and from there, distribute the power 
through extension cables and plugging boxes to various places on the 

At this studio we have eliminated a great portion of the labor 
necessary to cable a set by installing a permanent remote-control 
switchboard and cable system. On the platform above the set are 
cabinets containing sixteen magnetic contactors connected to 
the supply feeders from the power-house and controlled by push- 
buttons. To each contactor are connected four box cables, sixty- 
four cables in all. These box cables are spread over the bridges so 
that they cover the entire stage. When cabling a set, it is necessary 
for us only to drop the boxes, which are coiled on posts on the bridges, 
let down the buttons that control the contactors to which these cables 
are attached, plug in the lamps and we are ready to shoot. All 
stages at Universal are so equipped, and the problem of cabling a 
set is, to us, a very minor one. 


Now just a word about the "gaffer." The gaffer is the electrical 
department's representative on the set, and is the man in full charge 
of all electricians and equipment used by the unit to which he is as- 
signed. He must be a combination of lighting expert, electrician, 
economist, and psychologist. He must manage his unit with a mini- 
mum number of men and in such a way that we do not exceed our 
budget. He must be able to keep his unit operating on locations, 
despite breakdowns of equipment or other unforeseen problems. He 
must know all the tricks and moods of his cameraman so that he can 
anticipate every wish. And last, he must watch the general light- 
ing of the set and keep it right, despite the constant moving and 
shifting of lights, so that the cameraman may concentrate upon the 
finer details of his art. 

MR. TASKER : According to the program there should now follow a 
discussion of "Lighting for Long Shots and Close-Ups" by Mr. Val- 
entine, cinematographer; "Sound Pick-Up on a Production Basis," 
by Joseph Lapis, Production Mixer, and "The Director's Problem," 
by Henry Koster, Director. This discussion will not be in a form of 
a series of papers, but rather a running demonstration of the manner 
in which an actual scene is made. Mr. Valentine and his assistant 
will attend to the lighting. Mr. Lapis and his assistants will attend 
to the sound equipment, and Mr. Joseph Pasternak, associate pro- 
ducer on the picture One Hundred Men and a Girl, will pinch-hit for 
Mr. Henry Koster, who, unfortunately, is too ill to be present this 

In addition to these gentlemen, I am happy to present to you our 
cast for the scene Miss Deanna Durbin, whom you have already 
seen earlier this evening, and Mr. Mischa Auer, whose amusing an- 
tics have entertained you in previous pictures. In this scene, Mischa, 
who is a life-long friend of Deanna's father, both of them being unem- 
ployed musicians, is seated at the piano playing an accompaniment 
to Deanna's song Sunbeams. This is the same song that you heard her 
prescore a few minutes ago. We shall use the disk record that was 
made at that time for Deanna to sing to in just the manner described 
by Mr. Brown. 

After Mr. Tasker's introduction, the camera, sound, and lighting crews went about 
the business of making a long shot of Miss Durbin singing "Sunbeams" with Mischa 
Auer at the piano, under the direction of Mr. Pasternak. As they went about their 
work they explained many points concerning the technic and the reasons for it, and 


answered a number of questions from the audience. ' After the long shot a new set-up 
was made for a close-up of Miss Durbin, repeating a portion of the song. The dif- 
ference in lighting technic, sound pick-up, etc., were explained. 

At the conclusion of the demonstration the audience reconvened upon stage 10 
where the scenes made during the foregoing demonstration were projected. They were 
first shown in the form of "dailies," take by take, exactly as photographed, 
showing the slates identifying the scene numbers and other information. The cut 
sequence was then projected, 'from which the slates had been removed and into which 
several takes had been intercut into a continuous scene, as would appear in the finished 

(It is hardly necessary to state, of course, that the finished scene, as projected, was 
not the actual one shot during this evening's session; such would have been impossible 
in view of the time required for processing, etc.). 

MR. TASKER : It must be evident by now that the mere taking of 
a scene on the stage does not constitute a completed picture, but 
that there is a tremendous amount of finishing work that must be 
done before the picture is ready to be shown in the theater. What 
happens next is the function of the editorial department. Mr. 
Maurice Pivar, supervising editor of Universal Pictures, will dis- 
cuss the subject of film editing, followed by a demonstration of some 
of the work. 



Film editing is perhaps one of the few branches of the motion pic- 
ture industry that are least appreciated by the layman. The efforts 
of the director, the writer, the actor, and the cameraman are clearly 
defined upon the screen, and the layman is at all times fully aware 
and, in fact, appreciative of their contributions toward the success 
or failure of the picture. True, the film editor's name always appears 
upon the screen, but very few persons know of the intricacies in- 
volved in his share of the work in making the picture. To them he is, 
perhaps, just another cog in the wheel. On the other hand, those 
who have had occasion to contact with the editorial department of 
any studio will admit that the film editor is more than merely a 
cog in the wheel. 

Unlike most of the technical branches of the business, film editing 
does not follow any particular routine. Each picture and each se- 
quence of a picture present a different problem to the film editor, 

*Supervising Editor, Universal Pictures Corp., Universal City, Calif. 


especially so today, when the situations are tied up and involved 
with sound elements. 

The average successful editor must apply not only intelligence but 
ingenuity to his work. He must not only know the mechanical 
routine of editing but he must thoroughly understand and appreciate 
screen values whether they be dramatic, photographic, or other- 
wise, and must take full advantage of the film he has in hand so that 
it will play up to the audience to the best advantage. 

In other words, a proficient editor must be one who feels dramatic 
and comic impulses to the extent that he may convey these expres- 
sions to the screen to the best advantage. An editor of a picture who 
is devoid of this instinct would be of very little assistance to the 
average director, even though he may be fully versed in the general 
mechanics of editing. 

Those who are familiar with production are aware that the average 
feature picture involves approximately thirty thousand to sometimes 
three hundred thousand feet of film, and it requires efficiency and 
system for an editor to be able to place his hands upon any particular 
scene at any time, without having to wade through thousands and 
thousands of feet of film. The systems used for keeping track of 
this excess film vary in the different studios. At this studio we have 
systematized this phase of cutting through the cooperation of our 
laboratory and production departments. After each day's work 
on the set, the script girl sends to the editor a copy of her record of 
the day's work. This record records clearly the number, length, 
and dialog of each scene, and is kept on file from day to day by the 
editor. Time and again during the course of editing a picture, a 
director will wish to change a scene from one angle to another; and 
sometimes there is a question as to whether such a scene may have 
been shot, or whether such a scene was complete and to avoid wad- 
ing through the film to find the answer, the editor instead refers to 
the script girl's notes. 

In addition to the script girl's records, a laboratory record is also 
kept by each editor. This record is sent through with the film printed 
up each day by the laboratory (commonly termed "dailies"). 
The edge numbers and scene numbers of each scene printed are 
marked upon this record. These records are used for reference con- 
tinually while the picture is in the process of editing, particularly 
when reprints of certain scenes are required. ' 

Through the medium of these records, the editor is enabled, by 


checking the edge number on the film with the edge number on the 
record, to find the scene number of the particular scene required to 
be reprinted. Quite often during the editing of a picture, a scene 
is either damaged or, more often, cut up by the changing of cuts, to 
the extent that a reprint is necessary for practical handling. The 
laboratory records and the script girl's daily records facilitate order- 
ing these reprints and checking the various scenes of the picture. 

As we all know, in cutting a sequence a number of trims are left 
over from each scene. These trims, likewise, are kept in orderly 
fashion. The trims of each sequence are kept intact and labelled, 
then placed away with the name or number of the sequence. In this 
way, the editor, should occasion arise, can find the trims of any scene 
by looking through the trims of the sequence involved. If there 
should be fifteen sequences in a picture, the editor would have fifteen 
separate files of trims on hand in his cutting room. 

The mechanical routine involved in the preliminaries of editing a 
picture also vary somewhat in the different studios. The majority, 
however, favor the use of separate sound-track and separate action 
films during the process of editing. Several studios, however, use 
movietone prints prints that have the sound already printed on the 
film with the action. This method may be more economical from 
the standpoint of saving film, but I prefer the separate sound-track 
for the reason that it offers greater latitude in editing and makes the 
process of cutting more flexible. 

The first step in connection with editing, as a rule, is to synchronize 
the sound-track with the action. This is accomplished by the use of 
a mark or punch at the beginning of each scene. The punch or mark 
is made on both the action and the corresponding sound-track films, 
and it is necessary, therefore, to see that both punch marks are at 
corresponding points. 

To simplify handling separate sound-track and separate action, 
numbers on the edge of the film, spaced one foot apart, are necessary. 
These numbers are made in duplicate, and the same number that 
appears upon the edge of the sound-track film appears also upon the 
edge of the action film, identical numbers being in the same relative 
positions from the start marks. 

Two methods are used for placing the synchronizing edge numbers 
upon the film: (1) by a machine specially constructed for the pur- 
pose; (2) by printing the Eastman Kodak edge number (which is 
already on the sound-track) upon the action film corresponding to the 


sound-track. The latter method is used at this studio, and is regarded 
as the more desirable. The difference in the cost involved is negligible, 
yet the results attained by printing the edge numbers upon the posi- 
tive are by far better, because of the permanency of the numbers. 

With the dailies synchronized and properly numbered, they are 
then shown to the director or other executives interested in the pro- 
duction. When there are more than two takes to a particular scene, 
the director, as a rule, selects the one he prefers. It is then set aside 
for use in the picture, and the other takes are filed. 

The efficient editor, as a rule, begins to edit his picture upon the 
completion of a sequence. All the film of the sequence is assembled 
in continuity order. This gives the editor an opportunity to familiar- 
ize himself thoroughly with the film, and enables him to visualize 
the cutting possibilities of the sequence. The editor's objective, 
then, is to cut the sequence to the best advantage, utilizing such angles 
as he feels will present the sequence in the most effective manner 
upon the screen. 

This procedure is continued as the director shoots the picture, so 
that within a few days after the shooting has been completed, the 
film is practically ready to be shown to him in what is termed "first 
or rough cut." Most directors are thoroughly familiar with cutting, 
and at times are of great help to both the picture and the editor. 
The director, having made the picture, naturally may have his own 
ideas with regard to the choice of angles for presenting the scenes. 
In shooting the sequence, he may have been striving for certain dra- 
matic or comic values in the situation, and quite often the editor may 
have cut the sequence from a different point of view. This, naturally, 
brings about discussion and, with an intelligent editor, the director 
may sometimes find that the editor has already got the most out of 
the situation with the film in hand. Best results are generally at- 
tained when both the director and the editor work in close harmony 
and are open-minded to suggestions. 

The picture in first cut naturally runs considerably longer than the 
general releasing length, and before final eliminations are made the 
picture must be previewed ; in other words, presented to the public for 
the public's reaction. All further cuts or eliminations are determined 
by the effect of the picture upon the audience. Quite often certain 
situations that look very appealing during the process of cutting fail 
to impress the audience, and, conversely, situations that apparently 
do not seem to carry much weight in the studio projection rooms 


sometimes evoke strong reactions from the audience. Thus, through 
the medium of the preview, the director and everyone else concerned 
are enabled to judge the actual screen values of all the situations and 
business in the picture, and to decide which of them are not essential 
or effective. 

Before the preview is held, however, there is considerable mechani- 
cal work through which the picture must go. First is the work of 
embellishing and refining the various cuts in the picture. Then 
there is the matter of adding sound effects and music, and also of in- 
jecting certain photographic effects in the form of lap dissolves and 
other tricks to which the picture may lend itself. Today, with the 
perfection of optical printing, these effects which previously were pro- 
duced upon the sets by the directors and which proved very costly 
because of the time involved, are made on optical printers after the 
picture has been completed. The preparation of sound effects and 
incidental and other music and the dubbing of all the sound-tracks 
into a single track for the purpose of a preview and later for release, 
will be discussed later this evening by Mr. Edwin Wetzel. 

With the introduction of sound into pictures, the latitude of the 
editorial department has been lessened to the extent that where 
originally the possibilities of realigning and recutting silent pictures 
were unlimited, today we are confined more or less within the limits 
of dialog. For that reason, preparation for the production of pic- 
tures today is as vital as the actual shooting. Today, a script, before 
it is put into production, should be practically letter-perfect. While 
it is true that the average editor who knows his business thoroughly 
can, as a rule, overcome certain deficiencies in dialog or action, or 
both, by manipulating the film and sound-tracks, there are times 
when even the ingenuity of the editor is of no avail ; with the result 
that retaking the scene may be necessary, which, of course, means 
additional expense. 

The question of preparation applies also to timing the scenes on 
the sets. In the silent days, a director had to watch the positions 
of his actors when changing from one angle to another. He had to 
make certain that he picked up his actors in the same positions when 
changing the camera angle. Today, he must watch not only positions 
of the actors but also note the words spoken when the actor is in a 
certain position. Perhaps the greatest amount of grief that con- 
fronts the editor of today results from the apparent carelessness of 
some directors who overlook this vital point. To illustrate more 


clearly: Assume that the director is shooting a scene in which an 
actor is seated at a desk. The actor rises and walks across the room, 
during which bit of action the actor speaks certain lines, both when 
arising from the desk and when walking across the room. Now as- 
sume that the scene was a long shot, and that the director now wishes 
to shoot the same scene from a closer angle. Quite often we find 
that when the closer shot was made, the actor did not speak the lines 
corresponding to the action in the long shot. We may find that in 
the long shot certain words were spoken while the actor was rising 
from the deck; whereas in the closer angle the same words were 
spoken while he was walking across the room with the result that 
the editor is compelled to choose the scene in the angle that will not 
show a break in the action or the dialog, even though there may be a 
decided advantage in going to the other angle. 

Another point is the question of timing the dialog. Sound pictures 
call for more close-up action than the silent pictures. In order that 
the audience may be impressed by the delivery of lines, close action 
is very necessary and at times the director when shooting his close-up 
scenes may change his camera angle, showing the reaction of one of 
the actors to the words of another. The dialog may be very rapid, 
and the practice, as a rule, is to place the camera against the character 
speaking the lines while the other character answers the lines off- 
scene. When intercutting the two characters, and in order to regis- 
ter certain facial expressions (unless the director has emphasized 
these reactions and had the other characters off -scene pause suffi- 
ciently to allow for them), the editor is at a decided disadvantage, be- 
cause all that he can do in most instances is to cut from one angle to 
the other while the dialog is going on continuously. The editor's 
only alternative, as a rule, is to break the dialog by interspersing it 
with silent track to allow for the pause. Sometimes that can be done, 
but in most cases it is almost impossible, and it is needless to say that 
timing the dialog should not be dependent upon the editor but should 
be done on the set. 

The practical director today is one who appreciates thoroughly 
the limitations of cutting. Directors, however, differ considerably 
in their method of shooting. Some directors safeguard themselves 
by overshooting their pictures; that is, they shoot scenes from 
many different angles, for protection. Other directors, being more 
familiar with cutting pictures, cut most of their scenes in the camera. 
Both methods have their advantages and disadvantages. From the 


producer's standpoint, overshooting pictures is very expensive; and 
from the editor's standpoint, undershooting pictures causes untold 

Many obstacles arise as a result of the director's trying to cut the 
picture in the camera. In the effort to economize, the editor at 
times finds himself in the position of being limited in cutting the 
picture to the manner in which the scenes were shot by the director; 
and unless the director is perfect in his timing, we find when trying 
to connect certain scenes, that either the sound or the action does 
not match. It is always a very good expedient for an economical 
director, when attempting to cut his scenes, to overlap at least part 
of the dialog and action when progressing his scenes through various 
angles, and particularly to see that the dialog is timed perfectly with 
the action in each angle that he shoots. 

It is also a very good expedient for the director from the editor's 
viewpoint to shoot long scenes from at least two or three angles. This 
permits the elimination of dialog, if necessary. More than often we 
find that a lengthy scene that reads well on paper does not hold when 
recorded and shown on the screen, and unless the editor is protected 
by having a variety of angles, he has no alternative other than to let 
the scene run, as there is no means of cutting such a scene. Where 
there is a doubt in the mind of the director as to the merits of a lengthy 
dialog scene, he should by all means protect himself by shooting the 
scene from various angles. 

Some minor difficulties arise from time to time. One is the practice 
of directors at the end of a scene of yelling into a camera and not allow- 
ing the film to run a few additional feet. Sometimes the extra foot- 
age is very valuable when trying to carry out lap dissolves or fades. 
Some directors, likewise, have the habit, while a scene is going on, of 
cueing the actors during the pauses of dialog, with the result that 
sometimes the director's voice can be heard at the beginning of a 
line of dialog. 

These difficulties, as explained, emphasize all the more the impor- 
tance of preparation in the production of pictures today. Prepara- 
tion is the keynote to a successful picture. 

The mechanical features involved in editing pictures are more or 
less simple. They embody the use of the synchronizing machine, 
the moviola, the splicing machine, and the rewinder. These de- 
vices are very simple in operation, and require only a slight amount of 
experience to attain more or less perfection in handling them. 


We have explained previously the synchronization of film when 
received from the laboratory, but, in addition to that each cutter is 
supplied with a synchronizing machine, the purpose of which is to 
enable him to keep his film in synchronism as he handles it. The 
synchronizing machine can best be described as a shaft carrying any- 
where from two to four sets of sprockets. The editor, while handling 
his film, places both the sound-track and the action films over the 
sprockets, which keep the film in sychronism at all times as he passes 
the film from one reel to another during the editing. Should the 
film by any chance slip over the sprockets, the editor has the 
numbers on the edge of the film to guide him. This avoids the 
necessity of going back to the original start mark in order to check 
the sound-track with the action. 

Experienced editors, however, do not use the synchronizing machine 
much during the editing, but instead use the moviola. The practice 
is to place the sound-track film beneath the action film, both passing 
over the same sprocket wheel. Inasmuch as the sound-track film is 
clear, the light passes through it, and the editor is able to handle 
both sound-track and action films. He can also notice the modula- 
tions on the sound-track, and the average editor after a little practice 
becomes so adept and "film-wise" with regard to modulation of sound- 
track, that he can almost be certain, by noting the modulation as 
against the action, whether the picture is in synchronism or not. 

Some editors, however, might find it necessary, when three or 
more cameras are involved in shooting a scene and where there is 
only one sound-track for the three or four scenes, to use a synchroniz- 
ing machine that carries four sets of sprockets. The expert editor 
will cut the action without the use of these "syncing" machines and 
will match the film by action rather than by sound. 

As the editor proceeds with his cuts the successive lengths of film 
are temporarily fastened together by clips, after which the whole roll 
is patched on a modern splicing machine. This machine enables 
the assistant to make a thin patch that is generally more or less per- 
manent. All assistant cutters are familiar with the use of these 
splicing machines, and particular stress is laid upon the fact that the 
loss of frames must be minimized. Every time a piece of action is 
cut, there is a loss of one frame of film to allow for the patch. A 
careless assistant cutter will lose three or four frames, and for each 
frame that we lose we must insert spacers to keep the sound-track in 
synchronism with the action. The reason for trying to save the 


frames is not so much with regard to the ultimate release of the picture 
as for keeping the film in as good condition as possible for previewing. 
Scenes that contain an over-abundance of black spacers require re- 
prints so that the picture may be presented to the public in as clean 
a condition as possible. Reprints, however, involve expense, and 
whereas a single-frame spacer will pass through unnoticeably, 
spacers of greater length will be very noticeable and generally will re- 
quire reprinting. 

Two types of patches are used : one covering the full sprocket and 
the other covering the half sprocket. At this studio, we use the half- 
sprocket patch, and find it very satisfactory. It seems to pass 
through the projection machines more easily and has a long life. A 
full-sprocket patch is inclined to tear apart. The question of re- 
winding is very simple. Particular attention is called to the practice 
of tightening the film while rewinding, which causes scratches. This 
fault is avoided wherever possible. 

The satisfactory assistant cutter is one who exercises speed, care, 
and system in handling his film. System in a cutting room naturally 
results in cleanliness. Film at all times should be kept filed in cans 
and in fire-proof cabinets. Fire is a great hazard wherever film is 
handled, and it is important that the amount of film on hand be kept 
at a minimum. We can not emphasize this point too strongly. The 
efficient editor, with the aid of an able assistant, seldom has much 
film in the open at any one time. 

The following mechanical devices comprise the essential fittings 
of a cutting room: metal rewinding tables (each with one set of 
rewinders and racks for filing small rolls of film ; with either artificial 
or natural light in the background, facing the rack); steel cabinets 
for filing excess film; combination sound and silent moviolas; film 
bins; clips for fastening film together, preliminary to splicing; and 
the necessary reels required in handling the film. Give an efficient 
editor this equipment and one pair of scissors and no picture is 
too great a task for him. 

The writer has found it of great advantage to surround himself 
with men who have had a number of years of experience back of them. 
He finds that the longer the experience the greater their ability. An 
editor, handling one picture after another, continually encounters 
situations that perhaps have never confronted him before. Through 
his experience he becomes thoroughly familiar with dramatic, comic, 
and fast tempo situations. He becomes very confident in handling 


the cutting of these situations and at times is able to create situations 
in a picture that, from first appearances, the film would not permit. 
Summing up, a thorough knowledge of film editing is perhaps the 
best requisite for success in almost any branch of the production end 
of this business, and particularly where direction is concerned. Di- 
rectors who have risen from the ranks of editors are among the ace 
directors of the business, having found that their knowledge of edit- 
ing is of untold value to them in their work. 

MR. TASKER : When the film editor has finally finished his work, 
the next step is to prepare a musical accompaniment for the picture. 
This is the work of Mr. Charles Previn, who will discuss the problem 
of "Setting Music to Pictures." 



The scope of the subject of setting music to motion pictures is so 
broad that I hardly know where to begin. However, the picture is 
turned over to the music department, and we are told, "Well, here 
is a picture. Can you have the music all ready for it by tomorrow?" 

We then go over it with the director if he is available, or the as- 
sistant director, and others, and ask them to give us their ideas as to 
where music would help the scenes in the picture. Then I get an as- 
sistant cutter to time the sequences, which he does by running the 
film through a footage counter to measure the length of each scene to 
which we are required to put music. Then the length in feet is con- 
verted into seconds of time, so, as an example, we find that we have two 
minutes and thirty seconds in a given sequence to set to music. We get 
a complete idea of the picture, what it is all about the scenes, the 
dialog in different spots; and in writing the music try to catch the 
mood of the dialog and of the scene and plot. 

Sometimes the director himself does not know exactly what is re- 
quired. For example, I might be told that a certain scene was in- 
tended to be dramatic, and that I should build up the situation with 
dramatic music. Later, hearing the dramatic music I had put into 
the scene, he might say that it was too "heavy," that I had taken the 
scene too seriously; it was not what he wanted, but rather something 

*Musical Director, Universal Pictures Corp., Universal City, Calif. 


lighter. Then I would have to start at the beginning and do the 
whole thing over again. 

At this point, by way of illustration, a scene from "Wings over Honolulu" was pro- 
jected upon the screen. The sequence showed the scene of a quarrel between two lovers, 
and was projected first with a background of dramatic music and later with a back- 
ground of music in a lighter vein. 

The first music, whether you consciously recognized the fact or not, 
makes a very serious matter out of what is a mere lovers' quarrel. 
The situation was not very serious, and the picture should not give the 
impression that it was. When the director saw the scene with the 
dramatic music, he decided that it was too "heavy" and wanted us to 
lighten it a bit. The second score was the result, with a great im- 
provement, as you will agree. 

All the music for these pictures is originally written for the pictures, 
except in special instances such as in One Hundred Men and a Girl, 
for which Mr. Stokowski plays the classical masterpieces. In most 
of the pictures coming out of Hollywood nowadays, the music must 
be originally written for them. Every picture presents new problems, 
new thoughts, and new ideas, and the music to be written for it has, 
I might say, no yardstick. As I mentioned before, we measure the 
music by seconds, and for that reason we can not take any set music 
and apply it to a certain length of film. Besides, if we used the old mas- 
terpieces that have become so familiar, attention would be distracted 
from the picture to the music, because of familiarity with the music. 

In writing the music it is very necessary to do things mechanically 
up to a certain point, and then to forget the mechanical element. 
Writing the music into a given space of time is the mechanical part, 
but we must get. the feeling into the scene that the director means to 

At this point, and for further illustration, the scene from a picture "Parole" was 
projected, showing the effect of the background music in heightening the dramatic in- 
tensity of the scene. 

MR. TASKER: And now at last all the essential elements of the 
completed picture have been prepared, and we are ready to assemble 
a final sound-track to accompany the action. A number of persons 
are involved in this final step, including music cutters, sound-effects 
cutters, and the dubbing crew, and in charge of all these is the dubbing 
mixer. This final step will be described by Mr. Edwin Wetzel, 
dubbing mixer. 



The dubbing or re-recording process constitutes one of the final 
operations in producing a motion picture. It consists in blending 
additional sound effects and music with the dialog in order to match or 
enhance the pictorial effect that the director has achieved through 
the use of the camera. 

The process was developed shortly after the advent of sound. It 
was discovered that the necessity of moving the camera from one lo- 
cation to another, and the impossibility of predicting exactly how the 
picture should finally be edited, made it impossible to maintain a 
constant level or any semblance of smooth continuity in the added 
effects or background music if they were recorded at the time the 
picture was being photographed. 

When the picture is completed, so far as actual photographing is 
concerned, and when the editorial department has finished its work, 
the picture is then shown to the sound effects and music depart- 
ments, at which time is decided the nature of the effects and music 
that are to be added. 

The effects department then refers to the sound library to deter- 
mine which of the required effects are available from stock and which 
must be especially recorded to complete the picture in question. 
When this material is made available, it is then necessary for the 
sound-effects cutter to synchronize the various effects to the picture, 
and the number of sound-effects tracks he must build depends upon 
the number of effects that are to overlap in any one situation or se- 
quence of the picture. 

At this point a scene from "Wings over Honolulu" was projected, with dialog only, 
just as it was photographed and recorded on the set. The scene showed the interior 
of a house where a birthday party was in progress, Miss Wendy Barrie descending 
the staircase to join the party. A storm arises outside, during which Miss Barrie 
and Mr. Kent Taylor step to the veranda outside the house. A shift of scene shows 
an aeroplane landing near the house in the midst of the storm. 

During Mr. Wetzel's analysis of the scene, short samples of the individual sound- 
effects tracks were reproduced to illustrate the points made in the analysis. At the 
end of the presentation the scene was projected again, this time with all the various 
effects mixed together with the dialog at the proper points and in suitable intensities, 
just as they would occur in the finished picture. 

Analyzing the scene we find that in the interior of the home we need 
additional background voices coming from the guests (voices) and 
*Dubbing Mixer, Universal Pictures Corp., Universal City, Calif. 


dance music (music). Although this is a birthday party there is no 
pictorial evidence of the fact, so we must establish the fact off-stage by 
having an orchestra play and the crowd sing Happy Birthday (music 
and song) which evokes the laughter from Wendy Barrie on the stair- 

Later, the flash of lightning at the window establishes the fact that 
a storm is approaching, so a clap of thunder might be used (thunder] . 
Now we cut to the exterior, and perhaps the chirping of crickets 
might add to the general effect (effect] . Of course, we must continue 
the thunder and the music ; but now the music accomplishes two pur- 
poses : it adds to the romance of the veranda scene in addition to in- 
dicating that the party is still in progress inside. 

The significance of the succeeding effects is quite interesting. As 
Kent Taylor finishes the line, "Are you waiting for a knight to ride 
up on a white charger and carry you away?" everything happens at 
once a terrific flash of lightning accompanied by thunder, the rain 
falls, and you see an aeroplane approaching (effects; singly, then com- 
bined}. The combined sound-effects are used not only to match the 
action on the screen but to act as a fanfare ushering in the hero of the 

Note that while all this confusion is going on we must stop the 
music, because the director wants to create the impression that when 
the plane lands the two men will think that they are lost. If they 
were to hear the music coming from the house there would be no 
reason for believing so. 

MR. TASKER: It has been said that all that the picture industry 
has to sell are a few flickering shadows and a few undulated sound 
pressures. This evening we have taken you through the "House of 
Magic" where those shadows and pressures are created and where 
they are given vitality and meaning. We hope you enjoyed it, and 
we who presented this program to you were very, very glad to do so. 
I should like to express our own appreciation to a number of persons 
whom you have not seen tonight, but who have labored behind the 
scenes to make this meeting a successful one. A large number of 
people have contributed their time and efforts here this evening, as 
well as on previous evenings to prepare this program. They were 
very glad to do it for the Society, as typifying the spirit of the New 
Universal by the way in which the technical staffs have put their 
efforts together in this demonstration this evening. 



Summary. The Sub -Committee has investigated the possibility of adopting the 
SMPE standard perforation for negative film, and has come to the conclusion that vari- 
ous factors, especially the stock of background films, makes it impossible to use 
the SMPE standard perforation universally. 

The Committee now proposes that the rectangular perforation proposed by Howett 
and Dubray in 1932 be adopted as the standard perforation for both negative and 
positive. This perforation would operate satisfactorily on all apparatus designed 
for the Bell & Howett perforation, and should give little or no trouble on apparatus 
designed for the SMPE standard perforation. 

At the Fall Convention of the Society in 1931, a proposal was pre- 
sented by A. S. Howell and J. A. Dubray, recommending the estab- 
lishment of a single universal standard perforation. The Standards 
Committee took the matter under advisement and at a meeting held 
on June 2, 1933, a resolution was passed adopting the present rec- 
tangular positive perforation as a universal standard. 

Matters then remained at a standstill, mainly because of the diffi- 
culties encountered in inducing the owners of equipment in the field 
to alter their apparatus to conform to the present positive perforation. 
Cameras, in particular, presented the greatest obstacle because of 
their wide-spread use throughout the world and the difficulty of reach- 
ing the travelling cinematographers. 

It is the purpose of this report to discuss the registration of film in 
the various kinds of equipment in use in the camera and laboratory 
fields, comparing the behavior of the present perforations and present 
means of registration with the behavior of the perforation proposed 
herein and the same means of registration; extending the discussion 
to the behavior of the proposed perforation and the proposed improved 
means of registration. 


The dimensions of the proposed perforation can be simply expressed 
as follows : 

* Presented at the Spring, 1937, Convention at Hollywood, Calif.; received 
June 25, 1937. Prepared at the request of the Standards Committee. 



The universal perforation for both negative and positive film shall be rectangu- 
lar, shall be 0.110 inch wide by 0.073 inch high, and shall have rounded corners 
of a radius of 0.013 inch. 

The width of the proposed perforation is to remain the same. Its 
height is to be equal to the height of the present negative perforation 
and 0.005 inch less than that of the present positive. The radius of 
the rounded corner is to be within the chord height of the radial portion 
of the present 35-mm. negative perforation. Upon the fulfillment of the 

FIG. 1. 

Present and proposed perforations. In the lower right-hand corner 
the three perforations are superimposed. 

last condition depends the possibility of using the new perforation, 
without altering the existing apparatus, as effectively as the present 
dual standards. Fig. 1 shows the present and proposed perforations. 
In the lower right-hand corner of the illustration are the three per- 
forations superimposed, showing the coincidence of the radius of the 
rounded corners with the chord height of the radial portion of the 
present negative perforation. 


Pilot-pins of cameras are at present designed to fit the negative 
type of perforation as shown at the upper left of Fig. 2. The present 



pins could be used as effectively in the camera to register negative 
films perforated with the proposed perforation, as illustrated in the 
upper right-hand corner of Fig. 2, and the driving pins of the camera 
movement would perform similarly with both perforations. Equip- 
ping the cameras with the proposed driving and pilot pin, as illus- 
trated in the lower right-hand corner of Fig. 2, would result in an ad- 
vantage because of the decreased strain imposed upon the film as a 
result of variation in the dimensions and location of the perforations. 

FIG. 2. Relation of pilot-pins to perforations. 

The proposed pilot-pin would also assure lateral as well as longitu- 
dinal registration, particularly in camera mechanisms not equipped 
with edge-guiding devices. 

In this respect it may be noted that perforation by the Bell & 
Howell perforator is accomplished with a great degree of precision, 
there being practically no tolerances and the location of each succes- 
sive four pairs of perforations being controlled by four sets of pilots 
engaging in the four pairs perforated immediately previously. 

Since the proposed pins would bear on all four sides of the perfora- 
tion, greater assurance of perfect registration under all conditions 
would be. gained. It is to be noted, however, that the present pilot- 
pins would not be less effective with the proposed perforation than 


with the present negative perforation. This would not be so if the 
present positive perforation 0.078 inch high were used in conjunction 
with pilot pins 0.073 inch high, because the danger of error in longi- 
tudinal registration is as great as the difference between the height of 
the pin and that of the perforation. 

It must be borne in mind that the adoption of the universal per- 
foration 0.078 inch high would of necessity require the installation of 
new pins in all cameras, whereas the adoption of the proposed per- 
foration 0.073 inch high would not impose such change of pins as an 
absolute necessity, thus easing the burden on the owners of cameras 
scattered widely throughout the world. It would also be impossible to 
reach all cameras in use with any degree of promptness, and the 
consequences that may flow from this fact would be a serious re- 
sponsibility for the Society. 

One of the most important and relatively recent advances in special 
process cinematography is the background projection method. Per- 
fect steadiness of projection and perfect registration in the camera are 
essential requisites for the success of the process. Experience has 
proved that very accurate registering mechanisms are required in 
both cameras and projectors, and at the present time two alterna- 
tives are possible: (a) either the print to be projected must be on 
positive film perforated with negative perforations, or (b) the original 
negative must be photographed on negative film perforated with 
the present positive perforation and the camera movement equipped 
with positive driving and pilot pins. The use of different perfora- 
tions for negative and positive records always presents the possibility 
of inaccurate registration, which may act to the serious detriment of 
the finished picture. 

The establishment of a single universal perforation would remedy 
once and forever the anomalous situation now existing. In fact, 
all special photographic processes, such as multiple exposures, glass 
shots, color-separation processes, cartoon making, and many 
others too numerous to mention can be performed to the satisfaction 
of all their technical requirements and with assurance of perfect 
registration upon the adoption of the proposed perforation and the 
proposed pilot-pins. 


It is almost needless to point out that color cinematography would 



find great advantages in the proposed perforations and pins. In the 
various color processes using multiple negatives^ success in projection 
begins with proper registration, which can be done only by properly 
locating the film in the film-propelling mechanisms of all the apparatus 
used in the various operations of the process. The slightest inac- 
curacy of registration in any of these operations irremediably spoils 
the picture, and more precise means of registration would solve many 
problems, eliminate disappointments, and save much time and 







Sf 1 


[ J I \ PE/TFCCr ffllf 

\ no'\ \ m' 





FIG. 3. Errors of alignment due to splicing. 


Splicers are now equipped with pilot-pins for either negative or 
positive perforations. It is only in the large laboratories, however, 
that a distinction is made between the one type of machine and the 
other. Most small laboratories use splicers equipped with negative 
pilot-pins for splicing films having either negative or positive perfora- 
tions. It is obvious that serious errors may result from this pro- 
cedure. These errors are illustrated in Fig. 3. 

The upper left-hand corner of Fig. 3 illustrates the error occurring 
when two films having the present positive perforations are spliced 
with a splicer equipped with negative pilo't-pins. The inaccuracy of 


alignment is evident. More serious is the error that occurs when a 
film having the present positive perforations is spliced to a film 
having the present negative perforations, as illustrated at the lower 
left-hand corner of Fig. 3. A universal perforation and proper pilot- 
pins would completely eliminate these errors, and there would be no 
need of discriminating between splicing machines, except as regards 
setting the splicer cutting blades to the proper width of the splice. 


The printers most used in the film processing laboratories are of 
the continuous type, and guide the film at the printing aperture by 
means of a 64-tooth sprocket. The sprocket diameter, pitch, and 
form of the teeth, and the arc of contact of the film with regard to the 
number of teeth engaged, together with the carefully adjusted film 
tension, provide accommodation for the shrinkages of both negative 
and positive films, predetermined, with reasonably extended per- 
missible tolerance for undetermined shrinkage. This controls the 
longitudinal registration of the film, in all its complexities, with suffi- 
cient accuracy, but does not assure constant and precise lateral loca- 
tion of the film. Because of the double perforation standards and 
because of the variable shrinkage of the film, the sprocket-tooth 
form is necessarily a compromise designed to cope with undesirable 

In the upper left-hand corner of Fig. 4 is shown a comparison of a 
main printer sprocket tooth engaging the negative perforation and a 
positive perforation, the latter shown in dotted lines. The thickness 
of the tooth is calculated to provide proper clearance for predeter- 
mined shrinkages, and its faces are designed to offer bearing surfaces 
on the sides of the negative perforation so that the negative film will 
be well located and well guided throughout its run, and the possible 
lateral tolerances be so small as to be not only negligible but suitable 
for smoothly stripping the film from the tooth. The positive perfora- 
tion, on the other hand, because of its rectangular shape, presents the 
possibility of two locations for the sprocket tooth, with either side of 
the perforation in contact with the tooth as illustrated in the lower 
left-hand corner of Fig. 4. The full-lined perforation represents one 
condition and the dotted-lined perforation the other, the difference 
in lateral registration being as great as 0.004 inch. 

This does not mean that once the printer is threaded, the film may 
sway laterally back and forth, but it does mean that in the threading 



operation the film may be placed in either position. The variation 
in the position of the film is not seriously detrimental, considering the 
present dimensions of sound-films, because the difference between the 
width of the sound record and that of the scanned area offers ample 
protection against the 0.004-inch possible difference in locating the 
positive film on the printer sprocket. Push-pull sound-track dimen- 
sions do not, however, allow such protection, and the maximum toler- 
able difference in lateral location of the film is reduced to 0.0015 inch. 

FIG. 4. 

Engagement of printer sprocket teeth with proposed and present 

It is true that the present practice is to re-record the original push- 
pull sound record, but to all indications direct reproduction of the 
push-pull track in theaters is only a matter of time and will be stand- 
ard practice in the majority, if not in all, auditoriums in the not 
distant future. 

The adoption of the proposed universal perforation for both nega- 
tive and positive films will permit altering the teeth of the main 
printer sprocket to the form shown at the right of Fig. 4. This 
would assure ample bearing surface on the side of the perforation, 
with a possible difference of 0.001 inch in laterally locating the film 
while accommodating a negative film shrinkage of 1 per cent. 


It may be mentioned here that present sound-recording film 
carries the present positive rectangular perforation, and that some 
continuous printers have been equipped with sprockets the teeth of 
which have the form that would be adopted as standard for printers 
with the acceptance of the proposed perforation. This is essentially 
true of the sound-head of the Bell & Howell automatic printer and of 
some of the Bell & Howell model D printers, which have been as- 
signed solely to sound printing in some of the major laboratories. 
However, this procedure eliminates the possibility of interchangeably 
printing sound-track or picture area as desired, and is obviously un- 
desirable in all instances and impossible in small or relatively small 
laboratories where economies of space and capital investment are of 
major importance. 

Again, as in other apparatus, the recommended modification of 
printer sprocket design would be a marked improvement in the print- 
ing process, but would not be essential. It is to be noted, however, 
that locating on the unmodified printer sprocket two films having 
rectangular perforations requires some care. Both films, negative 
and positive, should be so aligned that the sides of one row of perfora- 
tions, preferably those on the sound side, are in contact with the 
sprocket tooth, to avoid the possibility of error in the lateral location, 
which can be as great as 0.008 inch. 


The most serious objections offered to adopting the proposed 
universal perforation were expressed by projector manufacturers, and 
were based upon the assumption that because of the reduced height 
the proposed perforation would interfere with the proper running of 
positive film that had shrunk considerably. The universal perfora- 
tion was proposed to the Society in 1931, after an extensive investi- 
gation of the then-prevailing shrinkage characteristics of positive 
film, and particularly of films that were nearing the last stages of 
their useful lives and in which the shrinkage had become considerable. 

It is an accepted and proved fact that present films are much stabler 
and shrink less than films of past years. Improved methods of 
handling films in exchanges and in projection rooms, and a better 
understanding and appreciation of the necessity of handling films 
properly have in recent years practically eliminated the possibility 
of finding prints in theaters that have shrunk so badly as to prevent 
their use in a projector without mishap. Furthermore, it is quite 



impressive to note that Technicolor release prints are printed on films 
bearing the present standard negative perforation 0.073 inch high, 
and that no inconveniences or trouble have ever been encountered 
in this respect in their long-run projection lives. 

The left portion of Fig. 5 shows the possibilities of interference of 
the projector sprocket teeth with the proposed perforation. The 
upper left section of Fig. illustrates the condition that exists when 


unshrunk 35-mm. film bearing the proposed perforation is driven by 
a 16-tooth feed or intermittent sprocket of SMPE standard design. 
Exact registration is maintained, as the perforation pitch is equal to 
the pitch of the sprocket teeth. 

However, such a condition is never encountered in actual practice, 
and the second section of Fig. 5 shows that with a film that has 
shrunk l x /2 per cent, which is the maximum shrinkage encountered 
today, tooth interference takes place in the 16-tooth feed and inter- 
mittent sprockets at the 8th tooth. The maximum number of teeth 
in mesh in most projection machines is 6 for the feed sprocket and 5 
for the intermittent sprocket. With the proposed universal perfora- 
tion and the present standard design of sprocket teeth, there is, there- 
fore, a considerable margin of safety to cope with the very rare in- 
stances in which films that have shrunk more than l l / 2 per cent 
would have to be projected. 

The condition is different with regard to the projector take-up 
sprocket, because the function of the latter differs considerably from 
that of the feed and intermittent sprockets. The third section on the 
left of Fig. 5 shows that unshrunk 35-mm. positive film bearing the 
proposed perforations would encounter interference with the 8th 
tooth of the take-up sprocket. The last section of Fig. 5 shows that 
enact registration is attained with film that has shrunk \ l /z per cent. 

It is quite apparent from these data that no ill effects are to be ex- 
pected from the adoption of the proposed perforation with regard to 
projection apparatus now available and in use. With a view to the 
future, the proposed perforation would offer possibilities of guiding 
the film in projectors more effectively and exactly by letting the pre- 
cisely located sides of the perforations control the position of the film 
instead of guiding the film on the edge, as is the present practice. 

Referring to the right-hand side of Fig. 5, the top section shows 
that negative film that has shrunk Y 4 per cent would be ideal for a 
32-tooth camera sprocket. The second section on the right-hand 
side of Fig. 5 shows that except for unshrunk positive raw stock the 
registration would be perfect for the 64- tooth main printer sprocket. 
The third section shows that negative film shrunk l /% per cent would 
interfere with the 81st tooth of the 64-tooth printer sprocket, and 
that a l / 3 per cent shrinkage would be ideal. The lowermost right- 
hand section of Fig. 5 illustrates the conditions encountered with the 
64-tooth main printer sprocket and an unshrunk positive film with a 
Va per cent shrunk negative. 



The problem of using stock negatives bearing the negative type of 
perforation is perhaps the most difficult to solve, particularly in such 
cases where it is necessary to intersperse such negatives with negatives 
bearing the proposed universal perforation. The problem to be 
faced by the industry would have to be faced regardless of the di- 
mensions of the rectangular perforation ultimately adopted as 
universal, whether the height be 0.073 or 0.078 inch; and would be 
more serious with the former, which is the one recommended in this 
report. However, the advantages to be derived from adopting the 
0.073-inch perforation in all other phases of motion picture work are 
so outstanding that it is believed that they justify taking means of 
adapting the existing stock negatives to a new perforation technic. 

The proponents of the proposed perforation in 1931 pointed out 
the possibilities and suggested means of reperforating the stock nega- 
tives with the proposed universal perforation. The question of re- 
perforating is rather serious, as at best it would be rather costly and 
some risk would be involved, particularly if the stock negatives to be 
reperforated are old and overshrunk. It is believed that the re- 
markable progress made recently in duplicating negatives offers the 
logical solution of the problem, and perhaps the most advisable. 
Duplicating stock negatives or using them for reprinting when the 
two types of perforation are not interspersed, could be done on a re- 
serve printer the sprockets of which have not been altered to the new 
perforation. This machine could be retained during the transition 

This analysis of the proposed universal perforation and its advan- 
tages are submitted to the Society and to the Standards Committee 
with the recommendation that the proposed perforation be adopted 
at as early a date as possible, so that new avenues may be opened for 
further advances in the technic of motion picture making in its many 
phases. Progress in the photographic, sound, and color fields will 
be hampered and retarded if the present dual standard is permitted 
to exist for any considerable length of time. 

J. A. DUBRAY, Chairman 


MR. SKINNER: It will be much easier to make a continuous sprocket for 
printing with this method because a flat side of an accurate part will be available, 


and we shall not get into the embarrassing situation- of having to use some sort of 
turning tool to cut the teeth in order to get the Bell & Howell perforations. 

MR. TOWNSLEY: It is slightly easier to produce an accurate continuous 
sprocket with this new tooth. 

MR. SKINNER: Have any instruments been made to punch these perforations? 

MR. TOWNSLEY : I believe the Eastman Kodak Company has a set of dies for 
the new perforation. It is no more difficult to make punches and dies for this 
perforation than for the present rectangular positive perforation. The perfora- 
tion has been made for a number of years, and the punches present no difficulty in 

Except for the most rigid requirements, we believe that the present negative 
pilot-pin will be perfectly satisfactory for this perforation. There is, of course, 
the possibility that continual use of a negative on a pilot-pin machine such as a 
step printer will result in slight wearing of the perforations. 

MR. FRAYNE: It so happens that I am a member of a Committee of the Acad- 
emy on sound-track dimensions in push-pull work, and the question has been 
raised as to whether or not, in printing, we should use the sprocket or the edge- 
guide. With this new sprocket in the printer the guiding is done by the tooth, 
and then in the reproducing machines by the edge-guide, and we finally get into 
trouble because of errors in the perforations of the film. Has the Committee 
given any thought to using the edge-guide instead of the sprocket? 

MR. TOWNSLEY: I believe the Committee has given that some thought. 
There is on the market a continuous printer the sound sprocket of which is 
equipped with this proposed tooth. Using sound recording stock bearing the pres- 
ent rectangular perforation, perfectly satisfactory prints were obtained. If a prin- 
ter such as the Bell & Howell model D printer is used, with teeth designed to 
accommodate both positive and negative perforations, excessive side weave results; 
but with the proposed rectangular tooth, which registers by means of either side 
of the rectangular perforation, the weaving was insufficient to cause trouble in the 
projection, even though the guiding in printing was done by the sprocket teeth 
and in reproduction by the edge of the film. 

MR. REMERSHEID: What is the difference in width of this sprocket tooth com- 
pared with the old one? 

MR. TOWNSLEY: The old or negative sprocket tooth, the tooth designed for 
the Bell & Howell perforation, measures 0.106 inch across the outside of the tooth, 
and the proposed tooth measures 0.1089 inch, or practically 0.109 inch across the 
tooth, so that there is a maximum displacement of the positive with respect to 
the negative on the proposed tooth of only 0.002 inch. 

MR. TASKER : I wonder whether the fact that the non-slip printers are ap- 
parently destined to handle most of the sound-film of the future, does not mean 
that we are no longer very much interested in sprocket-hole guiding in printing 

MR. TOWNSLEY: The advantage of the proposed perforation is that it will 
run on any present equipment just as satisfactorily as the old double 
system of perforations. The results with the new tooth are superior to the results 
attainable with either the proposed perforation or the old perforation on the 
present equipment designed for the combination of positive and negative perfora- 


Summary. A description of a new type of dynamic light-valve with oil-damped 
mirror used in the "Eurocord" recording equipment. Damping by oil, though in- 
fluenced by temperature, is compensated automatically. 

Electrodynamically actuated vibrating mirrors, operating accord- 
ing to the principle of the "Blondel" type of loop oscillograph, have 
a number of advantages over vibrating mirrors actuated by oscillating 
iron armatures. The driving force is very accurately proportional to 
the current, and, furthermore, acts directly upon the vibrating mirror. 
Indications of hysteresis and other amplitude distortions are com- 
pletely eliminated. When the oscillatory system is at rest no forces 
act upon it other than a strong elastic force that maintains the oscil- 
latory system very steadily at its zero position, the value of which 
can accurately be determined. Another advantage is that the loop 
represents an ohmic resistance over the whole frequency range, be- 
cause any reactions caused by oscillation of the two ribbons of the 
loop may be practically neglected, and, as a result adaptation to the 
amplifier becomes quite simple and can be effected with a high degree 
of efficiency. Considerations of this sort made it appear worth while 
to endeavor to improve the loop oscillograph as applied to the field 
of sound-films. 

A deciding factor in determining the dimensions of a design de- 
scribed herein was the size of the vibrating mirror. From optical and 
photographic considerations, an area of 2.5 sq. mm. was decided upon, 
preferably circular or square, so as to take full advantage of the light- 
beam. A rectangular mirror having its longitudinal axis parallel to 
the ribbons would be desirable, as such a shape would reduce the 
moment of inertia to a minimum. These two conditions being con- 
tradictory to each other, a compromise was effected in a rectangular 
shape having an area of 2.5 sq. mm. A mirror so shaped is well 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received June 
30, 1937. 

** Klangfilm Gesellschaft mit beschrankter Haftung, Berlin. 



covered when illuminated by the usual tungsten coiled-wire filament ; 
however, the moment of inertia is not small enough to allow locating 
all the resonances above the upper limits of 10,000 cps. Of course, it 
is advisable to place the fundamental frequencies as high as possible, 
if not altogether outside the range, thus avoiding complicated dis- 
tortion-correcting devices in arriving at a flattened frequency curve. 
Simple damping answers the purpose. The main portion of the 
frequency curve, right from the beginning and under all circum- 
stances, appears as a straight line. Considerations of this sort led 
to choosing for the damped loops a fundamental frequency of 7500 
cps., and resulted in a frequency curve practically flat up to 10,000 
cps. This was accomplished by a damping method to be described 
later, which in no way was influenced by temperature changes. 

In arriving at the dimensions of the ribbons it is important to use 
as little power as possible for operating the oscillograph so as to per- 
mit building apparatus that would be light in weight and easily 
portable. However, since in the present case the power required is 
less than 0.5 watt, there is no advantage in reducing it still further, 
as the weight thus gained is insignificant compared with that of the 
entire apparatus. There is therefore no necessity of insisting upon 
a loop system having a maximum efficiency from an electromechani- 
cal standpoint; but it is quite essential to make use of as much power 
as possible for operating the apparatus in order to gain a large rotat- 
ing angle. The greater the angle through which the vibrating mirror 
operates, the easier it is to effect a favorable and reliable construc- 
tion of the comb-shaped shutter and the noiseless shutter. The 
power carried by the loop is not governed by considerations of stress 
and strength, but solely by the heating effect of the current. Exces- 
sive current impulses of short duration therefore are not important. 
The design of the ribbons is therefore determined solely by the in- 
crease of temperature resulting during steady full modulation. For 
that reason an effort should be made to dimension the ribbons so as 
to present large heat-radiating surfaces. 

Further design features of the apparatus depend upon the following 
considerations: The thickness of the ribbons must be kept within 
such limits as to prevent their tendency to uncoil from causing irregu- 
larities in the deflection of the supporting spring. Furthermore, the 
width of the magnetic air-gap is determined by the width of the 
mirror, as the latter is located at the most effective point in the length 
of the ribbons the center. It is not possible to make the central 



[J. S. M. P. E 

part of the air-gap narrower than is required by the width of the 
mirror; . and it is hardly worth while to provide specially shaped pole- 
pieces, considering also the decrease of efficiency near the edges of 
the ribbon. 

Taking all this into consideration we arrive at a shape of loop as 
shown in Fig. 1. The aluminum ribbons are clamped along the line 
2-2, at which point, also, the current enters and leaves. The ribbons 
are made of round wire, flattened in a special device. At 6, where 
the material is left rounded, the loop can easily be suspended from a 
hook, which transfers to the ribbons the constant tension of a flat 
spring. At section 4-4 the ribbons pass over a bridge, which de- 
termines the oscillating length 2-4. The unused portions of the 

FIG. 1. (Left) Diagram of loop with mirror. 

FIG. 2. (Right) Means of obtaining additional damping of the 


ribbons, representing a total loss, are limited to the short bend at the 
hook. Cementing the mirror 3 to the ribbons would result in optical 
distortion caused by deformations at great amplitudes. Two causes 
are responsible for this: first, mechanical distortion of the ribbons 
during oscillation, since the twisting naturally would react upon the 
mirror; and, second, distortion caused by heat, which would in- 
fluence the entire system of mirror, cement, ribbons, etc., due to the 
differing coefficients of expansion of the several materials. For 
these reasons the mirror is fastened to the ribbons at two points only, 
as indicated in Fig. 1 by the small circles 5. At these spots, small 
round pads punched out of impregnated paper are inserted between 
the mirror and the ribbons by means of cement that will not soften 
at temperatures lower than 100 C. The mirror is cemented to the 
ribbons in a special device and at the required high temperature, so 
as to assure positioning it correctly and exactly parallel to the ribbons. 


However, no matter how carefully the cementing is done, inac- 
curacies will occur during the process, especially as regards the ab- 
solute parallelism of mirror and ribbons. Two means for a final and 
accurate optical adjustment have therefore been provided, to be made 
after the mirror has been cemented in place, by which the mirror can 
be turned slightly around its longitudinal and transverse axis. The 
bridge 4-4 (Fig. 1) has been so arranged that it can be raised and 
lowered by means of a screw, turning the mirror about its transverse 
axis. The mirror can be turned also about its longitudinal axis, for 
which purpose the bridge, hook, and tension spring are mounted on a 
brass plate resting upon two balls and able to swing around. The 
longitudinal axis of the mirror coincides with the centerline through 
the balls. Any adjustment of the screw, therefore, will swing the 
brass plate around, thus causing slight torsion in the loop, which, in 
turn will cause the mirror to swing around accordingly. 

'/ fe *3 

FIG. 3. Amplitude of bimetallic spring: 
ordinates, distance of plate; abscissas, tempera- 

In order to damp the natural oscillations, the loop is submerged 
completely in oil, and for this purpose the housing of the loop is al- 
most completely oil-filled. Part of the housing is left free from oil 
so as to permit the oil to expand with rising temperature; but re- 
gardless of the position of the housing, there is no possibility that any 
oil bubbles will arise to cause interference. As shown later, there is 
very little space left for the oil in front of and behind the loop, and 
therefore the capillary forces existing will prevent air bubbles from 
entering these narrow spaces. 

For damping the loop a rather thin oil is used having a low con- 
gealing point so as to make the system work even at low temperature. 



[J. S. M. P. E. 

For normal temperatures, damping by oil alone would not be sufficient, 
so additional means of damping have been provided : one adjustable in 
itself, but initially adjusted for a fixed amount of damping; the 
other adjusted automatically according to the prevailing tempera- 
ture. In both cases the desired increase of damping, i. e., friction, is 
achieved by moving small plates closer to the loop, thus decreasing 
the oil-space in front of or behind the loop. As the space for the oil 
becomes narrower, resistance to its flow increases, which, in turn, in- 
creases the damping of the mirror since the latter can move only when 
the oil has a chance to move with it. In such manner quantities of 

FIG. 4. Arrangement for temperature 
calibration: lower compartment, pump; 
upper compartment, loop. 

oil oscillate with the loop, but their movements serve still another 

Near the edges of the ribbons and the mirror, small eddy-currents 
occur in the liquid, resulting in considerable circulation of the oil. 
This aids materially in cooling the loop, especially if (and such is here 
the case) the metal submerged in the liquid is a good conductor of 

Fig. 2 shows schematically the arrangement of the fixed and the 
variable damping method. The mirror 1 is fastened to the ribbons 
2 (shown in Fig. 2 in side view), and the surface of the lens 3 is moved 
more or less toward the mirror by means of a screw-thread 4, until 
the desired amount of damping has been effected. On the opposite 
side, a copper plate 5 is arranged so that it can be moved toward the 
ribbons 2. This is done by means of a bimetallic spring 6, against 

Oct., 19371 



which the guide rod 7 of the copper plate is pressed steadily by the 
flat spring 8. 

Rising temperature causes the bimetallic spring to bend, thus 
decreasing the distance between the ribbons 2 and the damping plate, 
while the friction of oil increases as compensation for the decreasing 
viscosity of the oil. 

In order to provide adequate compensation within greatly varying 
temperatures it became necessary to subdivide the movement of the 
bimetallic spring into two ranges. In one range the spring is much 
more sensitive to temperature than in the other. This is achieved by 

Dnibtl *"- 

FIG. 5. Amplitude vs. distance of damping 
plates: ordinates, amplitude; abscissas, distance of 
damping plates in n. (Lens distance SOM; +5 C; 
frequency 7500 cps. ; sollwert rated value.) 

means of the regulating screw 9 (Fig. 2). The situation is shown 
schematically in Fig. 3, curve 1 of which indicates the movement of 
the damping plate as it would be for ideal temperature compensation. 
On the X axis are laid out the different temperatures, on the Y axis 
the distances of the plate from the ribbons. The general characteris- 
tics of the curve are readily understood : At very low temperatures 
the plate should remain at an infinite distance, because no additional 
damping is needed. With rising temperature this plate at first ap- 
proaches very rapidly, later more slowly, because its influence upon 
damping is little at the start and increases more and more the closer 
it approaches. The curve 1 approaches therefore the zero axis 
asymptotically. The movement of the bimetallic spring is in exact 
proportion to the temperature, as shown in Fig. 3 by the two straight 



[J. S. M. P. E. 

lines 2 and 3: 2, which is rather steep, pertains to the temperature 
range tik; 3, less inclined, and corresponding therefore to a lower 
sensitivity to temperature, pertains to the temperature range from 
fe/s. The steady and regular curve 1 is, therefore, approximately 
replaced by two straight lines intersecting at a point corresponding to 
the temperature k- At that temperature the bimetallic spring just 
touches the adjusting screw 9 (Fig. 2), which keeps the movements 
within certain limits. It is evident that the inclinations of the 
straight lines 2 and 3 in Fig. 2 are governed entirely by the dimen- 
sions of the bimetallic spring and by the position of the screw 9. 

FIG. 6. Temperature vs. distance of damping plates: 
ordinates, distance of plates; abscissas, temperature 
(centigrade). (Lens distance 85/x; frequency 7500 cps. ; 
sollwert = rated value.) 

Fig. 3, in the upper right-hand corner, shows schematically the ex- 
treme positions of the bends. The bimetallic spring is a combination 
of two different kinds of steel. For adjustment of the spring cor- 
responding positions of the screw 9 are provided. 

Final inspection of the instrument and its temperature calibration 
are done by means of the arrangement shown in Fig. 4. Water or 
other liquid at given temperatures circulates through the apparatus ; 
the oil container, surrounded by a constant flow of water, being left 
open so as to make possible calibration with a full oil container. The 
oscillations are observed from below. 

Curve 1 of Fig. 3 represents the movements of an ideally operating 
damping plate, but a further correction is necessary if it is desired in 

Oct., 1937] 



actual practice to ascertain the best possible approximation by two 
straight lines. It is evident that the discrepancies between the 
straight lines and the theoretical curve can not at all points show equal 
influence upon the frequency curve. When the damping plate is at 
some distance from the ribbons, small alterations of the distance are 
practically insignificant. Beyond a certain distance it would make 
no difference even whether the plate were in place or not. It is there- 
fore necessary to have some idea of the errors caused by discrepancies 
from the ideal curve. For this reason measurements as shown in 
Fig. 5 were made. At fixed frequency, constant temperature, and 
constant distance of the lens, the amplitudes are measured with rela- 
tion to the distance of the damping plate. The resulting curve 

FIG. 7. Cross-section through casing. 

shows plainly at what distance of the plate the amplitudes reached 
the rated value and at what distances errors of amplitude reached 
values of ==0.5 db., ==1.0 db., etc. The readings can be laid out as 
a set of curves as shown in Fig. 6. Here the curve shown in full line 
indicates the respective distances of the damping plate for an assumed 
case in which at all temperatures the rated value of the amplitude is 
reached exactly. Curves shown in dotted lines indicate the distance 
at which discrepancies from the rated value reach ==0.5 db. and ==1.0 
db. Of course, the discrepancies apply only to the upper end of the 
frequency curve of the light-control instrument. If for this range a 
tolerance of ==1.0 db. is permissible, then all that is needed is so to 
place the two straight lines 2 and 3 (Fig. 3) in the zone indicated by 
the two extreme curves that at no point of the temperature interval 
is the zone exceeded. After entering the straight line in its correct 
position on the sketch it becomes evident at what temperature fe 



(Fig. 3 ) the adjusting screw 9 (Fig. 2) should make contact. The 
exact angle of inclination of the two straight lines can be read off the 
chart, and there is no difficulty in determining the correct dimen- 
sions of the bimetallic spring if the constant of the material is known. 
Fig. 7 is a cross-section through the casing. The permanent mag- 
net is circular in shape, with two poles diametrically opposite each 
other. The upper cover is soldered to the casing after all final adjust- 
ments have been made. Strong connecting screws are mounted on 
the cover. Soldered connections are provided for the lead-wires 
between the terminals of the ribbons and the connecting screws on the 
cover, after the latter has been put in place. To make this possible 
the wires in question are led through in such a way as to protrude 
slightly through the oil inlet opening (not visible in Fig. 7) of the 

FIG. 8. Limiting frequency curves for 
the temperature range +1 to +35: 
ordinates, amplitude; abscissas, frequency. 

cover, and can readily be soldered with the cover in place before 
closing the opening with a screw cap. 

Fig. 8 shows two frequency curves of the apparatus. Within 
these limiting curves are located the frequency curves between +1 
and +36 C. 


MR. FRAYNE : What is the length of the bridge between points 2 and 4 on 
Fig. 1 ? What are the tension of the ribbons and the strength of the magnetic 

MR. LICHTE: The length of the ribbons is about four millimeters, the strength 
of the magnetic field about eight thousand gauss. I do not know exactly the 
tension of the spring. 

MR. ALBERSHEIM: What is the maximum angle through which the mirror 

MR. LICHTE: About one degree. 


Summary. Color photography applied to publicity stills represents a very valuable 
asset for the motion picture industry. The demand for high-quality results and speeds 
places color stills in a special class of their own, and therefore the discussion of the 
various methods of obtaining color -separation negatives is carried out essentially 
upon the basis of these requirements. For the production of sample prints on paper, 
many of the available methods are discussed, such as carbon, carbro, dye transfer, 
chemical toning, etc., emphasis being placed upon the methods that are capable of 
giving results most suitable to the needs of motion picture industry. The general dis- 
cussion and the extensive bibliography should be found valuable by those who wish to 
study the subject of color photography in greater detail. 

The increased interest and public appreciation of color photography 
during the last few years can very probably be attributed to the ex- 
cellent results attained with various color processes, which in turn 
have been made possible by the improvement of the photographic 
materials available. While no principles have been discovered that 
were not known twenty or forty years ago, in those days the com- 
paratively low speed of the panchromatic material and the limited 
variety available made impossible the realization of ideals, except in 
the case of a few experts who willingly sacrificed their time in order to 
produce something different. 

Color photography, as applied to publicity color stills, represents 
a very valuable asset for the motion picture industry. While the 
methods of arriving at acceptable results are many, the requirements 
of this industry can be regarded as in a special class by themselves. 
The following discussion of the most popular color processes is there- 
fore carried out essentially on the basis of these requirements. 

The literature of color photography is very extensive and very 
complete. Those who wish to begin with the fundamentals will find 
many text-books listed in the attached bibliography. The manufac- 
turers of photographic material are also issuing complete and detailed 
information of the uses of their products, and it will be found today 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received June 
30, 1937. 

** Consulting Engineer, Metro-Goldwyn-Mayer Studios, Culver City, Calif. 


398 0. 0. CECCARINI [J. S. M. P. E. 

rather a simple matter for anyone who cares to follow the instructions 
carefully, to produce acceptable color prints on paper. 

We shall begin with a brief description of the methods for producing 
color-separation negatives. The oldest known method is that of 
making three separate negatives in an ordinary camera, in succession, 
each with its corresponding color-separation filter. 

Next in line is the so-called "sliding or repeating back" which can 
be readily attached to any ordinary camera. This back carries the 
three color-separation filters, and a plate holder for a single long 
plate, or three separate plate holders adjacent to each other and upon 
which the exposures afre made. The operation consists in sliding 
back the required amount after each exposure, by hand or by means 
of an antinous release. Some time ago an automatic repeating 
back was introduced in England by the Color Photographs, Ltd., 
operated by clockwork, which performs all the operations automa- 
tically in a rather short period of time about two seconds, or slightly 
less. 1 

Obviously the use of separate plate holders in an ordinary camera, 
or of the usual repeating back, are applicable only to still-life subjects, 
but not very applicable to portraits. The automatic repeating back 
can be used satisfactorily for portraits in studios. 

Color-separation negatives, particularly for portraits, can be ob- 
tained also by means of the so-called color-screen plates, or color- 
screen films such as the Lumiere and Agfa color plates, Lumiere 
Filmcolor, and Finlay color plates, and the Dufaycolor film. The 
Lumiere. Agfa, and Dufay materials contain the color-filter elements 
in minute, irregular or regular geometrical patterns, these color ele- 
ments acting as taking filters as well as projection filters, after the 
reversal process. The Finlay plate uses as a taking filter a plate of 
geometrical pattern physically separate from the negative emulsion. 
Descriptions and uses of the color-screen plates and films can be ob- 
tained from the manufacturers of these materials. 

For reproduction work, or for producing color prints on paper by 
means of the original color-screen plate or film, it is necessary to 
produce color-separation negatives from the screen-plate or film. 
This is ordinarily accomplished by copying the original color-screen 
plate through three-color separation filters of very narrow trans- 
mission. The Finlay color plate is different in this respect, as color- 
separation negatives can be obtained from the Finlay positive by 
means of the so-called block-out screen. Although acceptable re- 

Oct., 1937] COLOR STILLS 399 

suits are possible by means of the color-screen method, the quality, 
however, is not comparable with that of the method of making color- 
separation negatives directly on three separate panchromatic emul- 
sions. The reasons are many but very probably the major one is the 
undeniably narrow range of sensitivity (latitude) of the emulsion of 
the color-screen plate or film. The Kodachrome film now available 
in 35-mm. and substandard sizes, but which will be available shortly 
as cut film, promises to be a medium vastly superior to the present 
color-screen material chiefly because of its continuous tone character, 
its high color-sensitivity and wide latitude. In the same class can 
be placed the new Agfacolor film recently announced. 

During the past few years Duf aycolor film has achieved great 
popularity due particularly to its increased speed, and also to the 
fact that its geometrical color-screen is extremely small and permits 
a certain degree of enlargement before the pattern becomes visible to 
the naked eye. It is a comparatively simple matter to carry through 
the various chemical operations and produce interesting color trans- 
parencies. Motion picture studios make considerable use of the 
Dufaycolor film by supplying it in the form of transparencies to pub- 
lishers, who, in turn, produce their own color-separation negatives 
for printing purposes in magazines, weekly periodicals, and news- 

Whenever high-speed and high-quality work is desired in motion 
picture studios, the color-separation negatives are made today by the 
so-called "one-shot" camera, of which several models in various 
sizes are available in the open market. This type of camera consists 
essentially of two partially reflecting mirrors disposed at convenient 
angles by means of which the cone of the light emitted by the lens is 
divided into three different components, each of which is directed to 
the appropriate filter and plate. It can be roughly assumed that 
about one-fourth of the light passing through the lens reaches each 
color-separation plate, since the partial reflecting mirrors cause a cer- 
tain loss of light. Taking an average filter-factor of five we can say 
that approximately one-twentieth of the light passing through the 
lens can effectively be directed onto each negative. A slight increase 
in overall speed can be attained by using for the blue-separation nega- 
tive a fast color-blind emulsion, and, therefore, employing a highly 
transparent first mirror, thus directing the bulk of the light to the 
second mirror, which divides it into suitable proportions for the 
green- and red-separation negatives. The use of two different nega- 

400 O. O. CECCARINI [J. S. M. p. E. 

tive emulsions required by this method is sometimes open to objec- 

It is universally accepted that the properly designed "one-shot" 
camera is the most useful and fool-proof instrument available today 
for producing color-separation negatives. Not only are three color- 
separation negatives of identical size obtained, but in each case the 
full range of the panchromatic emulsion is made use of for each nega- 
tive. In addition, if any slight movement or diffusion occurs in the 
background, or the foreground, it appears identically in all the three 
negatives, so that when superimposing the three constituent color 
positives, no color fringes are noticeable as happens sometimes with 
repeating backs. This type of camera, due to its complicated con- 
struction is usually very expensive, but as the primary cost of equip- 
ment used in the motion picture industry is of secondary importance 
to the quality of results desired, it can be completely discounted. 
This camera is available today in various forms, each inventor having 
attempted to minimize certain imperfections or disadvantages in 
favor of the others. Therefore, in this respect we find that personal 
opinion has played a great part in the arrangement of the mirrors 
and the geometrical outline. The design of the typical "one-shot" 
camera also dates back many years. A very interesting and com- 
plete description of the various forms of optical combinations sug- 
gested in the past can be found in Wall's History of Color Photography. 

It must be emphasized at this time that the following critical 
considerations about "one-shot" color cameras represent the personal 
opinion of the writer, and may be very much at variance with the 
opinions of other color workers. As already stated, we are at this 
moment considering the subject as applied to color portraiture for 
the motion picture industry. 

When choosing a "one-shot" color camera, several considerations 
must be given particular attention. In the first place, we are com- 
pelled to judge of very little value those types of cameras in which 
splitting the light-cone is accomplished by dividing the exit pupil 
of the lens into three different zones. This construction gives rise to 
the so-called "parallax," and only objects in the focal plane of the 
lens will superimpose correctly, but anything beyond, or near, will 
be displaced in opposite directions in the three negatives and will 
therefore produce color fringes. In addition, this particular design 
suffers greatly from unevenness of illumination throughout the area 
of the plate, so as to cause a predominance of one color on one side of 

Oct., 1937] 



the finished picture, and of the other colors on the opposite side. 
Cameras of this type have been in use in the past, and some are still 
available today. Although it is conceivable to think of subjects, por- 
traits, for instance, with a uniform background devoid of any pattern, 
we must admit that the field of application is extremely limited, 
because we are seldom at liberty to choose a background suitable for 
this type of camera. Experience and theoretical considerations have 
shown that a satisfactory image can be attained only by allowing each 
plate to encompass the full cone of light emitted by the lens. On the 

FIG. 1. "One-shot" color camera 
using crossed partial mirrors. 


FIG. 2. "One - shot" color 
camera with partial mirrors dis- 
closed one after another at an 
angle with the central axis. 

basis of these considerations we find the satisfactory "one-shot" 
color camera restricted to essentially two types : 

CO The type that involves crossed partial mirrors (Fig. 1.). 

(2) The type that has the partial mirrors disposed one after another at an 
angle with the central axis. The two mirrors may be parallel to each other, or at 
opposite angles. (Figs. 2, 3, and 4.) 

With regard to the last type, again we find cameras in which the 
first mirror toward the lens is placed at an angle of approximately 
45 degrees and others in which the same mirror is placed at an angle 
much smaller than 45 degrees. The deviation in the set-up is brought 
about by two major considerations. If the mirror is placed at 45 
degrees, the general appearance of the camera is a little more pleasing 
than if the mirror is placed at an angle of, say, 30 or 35 degrees. If 
the mirror is placed at 45 degrees or very nearly so, it can be readily 
proved geometrically that the light scattered by the color-filter inter- 



[J. S. M. P. E 

cepting the light from the first mirror is not directed toward the plate 
that intercepts the image formed by the second mirror. Therefore, 
the least fogging effect can be expected from this particular arrange- 
ment, and much less than if the mirror were at an angle of 30 or 35 
degrees. On the other hand, a mirror placed at 45 degrees does not 
give as uniform a reflection as if the angle were smaller. This point 
can be readily appreciated by computing the reflection of the bound- 
ary rays striking the mirror by means of the Fresnel formula : 

R = - 

rsin* (i - r) ton 2 (i - r)"| 
Ltn* (i + r) tan 2 (i + r)J 

where i and r are the angles of incidence and refraction. 

This difference in coefficient of reflection for different angles is 

FIG. 3. Mirrors at opposite angles. 

FIG. 4. Mirrors parallel. 

appreciably modified by the partial coating of the mirror. Never- 
theless, it is there to an extent that might, in the opinion of some 
workers, be deemed objectionable. Manufacturers who prefer to 
place the first mirror at angles smaller than 45 degrees contend that 
the light scattered by the glass surface on the filter will be again re- 
flected partially by the same mirror toward the lens, and only an 
extremely small percentage will reach the second plate and be entirely 
out of focus. The extremely small amount of fog that might be 
produced would be uniformly distributed throughout the plate and 
would not impair the quality of the image. Therefore, the uniformity 
of distribution of the light would appear as a more important require- 

The second mirror is invariably placed at an angle smaller than 45 
degrees, as the light scattered by the filter of the second plate does 
not ordinarily strike the back plate. 

Oct., 1937]' COLOR STILLS 403 

The type of camera with crossed mirrors has the chief advantage of 
permitting the use of lenses of short focal-length, which might be 
regarded as convenient for outdoor or landscape work. However, 
due to the form of construction, one of the mirrors in the camera is 
solid throughout, and the other one is split into two co-planar sec- 
tions, the joining point constituting a small vertical zone that inter- 
cepts the light from the lens. The joining line ordinarily does not 
constitute an objection except when the lens is stopped down to a 
very small value, in which case it might begin to cast a shadow in the 
middle of all the three plates. This ordinarily occurs at a stop be- 

As to the nature of the partial mirror, glass has been used by many 
manufacturers, while others prefer pellicular mirrors. Glass partial 
mirrors might give rise to double images, caused by the back surface 
of the mirror when the coefficient of reflection of the front surface is 
appreciably less than fifty per cent. The pellicular mirrors do not 
give rise to secondary images because they are extremely thin and 
the back image coincides with the front image. In the case of glass, 
however, the back image can be minimized in several ways. In the 
first place, we can use glass of low index of refraction ; or, we can use 
a softer glass of higher index of refraction and minimize the secondary 
image by changing the index of refraction of the back surface by 
evaporating onto the surface a transparent substance of low index, 
such as fluorite. 2 Another method consists of changing the index of 
refraction of the glass by a chemical treatment which in itself is 
nothing else but a microscopic etching of the glass. 3 Several chemical 
substances are known to produce this effect. If such procedure is 
decided upon the glass is first treated chemically so as to change the 
index at the surface boundary, after which the reflecting metal is 
evaporated or sputtered. The back surface reflection coefficient can 
be readily evaluated in terms of the index of refraction by means of 
the Fresnel formula given above. For comparing the behavior of 
two types of glass we can assume that the light ray is normal to the 
surface of the glass, in which case the formula becomes 

D ^ 

where n is the index of the glass. 

If the index of one glass is, for instance, n = 1.55, then R = 4.05 
per cent: while if the index is. say, 1.44, then R = 3.24 per cent. 

404 O. O. CECCARINI [J.'s. M. P. E. 

Thus we see that a small change in the index of the glass produces a 
correspondingly large change in the coefficient of reflection. 

Unquestionably, glass partial mirrors are always far more per- 
manent and dependable than pellicular mirrors, although with care- 
ful attention in handling, the latter type should also be found quite 

Glass partial mirrors introduce a slight distortion of the images due 
to refraction of the glass. However, when the thickness of the glass 
mirrors is not in excess of 0.050 inch, then the only correction usually 
necessary is readily obtained by tilting the plate receiving the image 
reflected by the second mirror. The through image is sufficiently 
compensated by the two mirrors, placed at opposite angles. 

For the surface treatment of mirrors, whether they be glass or pellicu- 
lar, several metals have been successfully used. Gold, for instance, re- 
flects a large percentage of orange-red light and transmits quite freely 
a blue-green light, and its efficiency becomes quite satisfactory in this 
respect by carefully choosing the sequence of the color-filters. The 
most efficient metal is silver, but since it readily tarnishes when ex- 
posed to air, it is necessary to protect it with some kind of lacquer, 
which unfortunately, unless very carefully applied, may change the 
optical quality of the surface. For that reason it has been found 
lately more practicable to use aluminum, which can be applied by 
evaporation in high vacuum; or a combination of aluminum and 
chromium, which adds durability; or chromium alone. Next to 
silver, aluminum is the most efficient and is quite stable. It has been 
found that aluminum-coated mirrors change very rapidly during the 
first few hours after treatment, and gradually become permanent as 
the transparent aluminum oxide forms and protects the remaining 
aluminum from being further oxidized in the presence of the air. 
Very probably the combination of aluminum and chromium can be 
regarded as the most satisfactory from the standpoint of hardness and 
general durability, although not quite as efficient as aluminum alone. 
In general, the efficiency of a partially aluminized mirror is of the order 
of 80 to 85 per cent. 

Partial reflecting mirrors made of glass can be further improved 
with respect to the secondary image by using glass colored in the 
mass. For instance, if the blue-separation negative is to be formed 
by the first mirror, we should use for this mirror a yellow-colored 
glass that would produce a secondary image of yellow color, which, 
in turn, would be absorbed by the blue filter in front of the negative. 

Oct., 1937] 



Similarly, if the reflection from the second mirror is to be used for the 
green-separation negative, we should use for the second mirror a red- 
colored glass, thereby producing a red secondary image, which would 
be absorbed by the green filter. This expedient of using colored glass 
is especially desirable when the percentage of reflection of each 
mirror is appreciably less than fifty per cent. In general, it is more 
expedient to reduce the secondary image by using a glass of low 
index, or by chemically treating the glass surface as previously indi- 

Another form of "one-shot" camera, not quite as expensive as the 
double mirror type, is one involving a single partial reflecting mirror 
(Fig. 5), and in which two of the three color-separation negatives are 
exposed face to face in the form of a 
bipack. Several arrangements can 
be made. For instance, the bipack 
can be made to record the green and 
the red sensation by exposing the bi- 
pack through a yellow filter and re- 
cording the blue sensation on a sepa- 
rate negative. For the blue-sensation 
negative we are then at liberty to use 
a panchromatic material in connec- 
tion with the blue filter, or we can 
use an ordinary color-blind material 
of suitable sensitivity. An alterna- 
tive arrangement would be to record 
the blue and the red with the bipack by exposing through a minus 
green or magenta filter, and then obtain the green-separation nega- 
tive on an orthochromatic or panchromatic material through the 
regular green filter. Whatever arrangement is used, the ratio of re- 
flection to the transmitted light of the mirror is to be arrived at by 
considering the relative speed of the bipack with its proper filter and 
the negative material chosen for the third negative. Manufacturers 
of bipack material give detailed information and usually supply the 
third film to be worked in connection with the bipack. 

The chief drawback of the single-mirror "one-shot" camera is with 
respect to the blue printer or red-separation negative. Since this 
negative (the second of the bipack) is appreciably diffused due to the 
scattering of light by front emulsion, the net result is a soft blue 
positive which might be considered undesirable with some subjects. 

FIG. 5. "One-shot" camera in- 
volving a single partial reflecting 

406 O. O. CECCARINI [J. S. M. p. E 

It must be remembered that the blue printing color is the one that 
contributes most to the definition. With suitable pressure in a plate- 
holder carrying the bipack, this softness of the blue printer negative 
can be appreciably minimized. Nevertheless, the peculiarity al- 
ways remains, and from that standpoint this method of making color- 
separation negatives can not be regarded as being ideal, although 
quite satisfactory results can be attained. As mentioned before, the 
initial cost of a high-grade three-color separation camera is quite 
secondary when considered from the standpoint of its application 
to the motion picture industry and, therefore, the double-mirror kind 
should be given preference to any other type. 

Having at our disposal a suitable color-separation camera, we shall 
proceed to determine the necessary requirements for obtaining a set 
of color-separation negatives of the proper quality for reproduction 

Exposure can be made with ordinary daylight, with flashlight, or 
with incandescent or photoflood lights ; but in no case should the lights 
be mixed, as falsification of color will invariably result. The manu- 
facturers of color cameras ordinarily supply sets of filters or com- 
pensation filters for use with the various kinds of illuminants. 

The theory of tone reproduction demands that the exposure of the 
negative material be confined within the straight-line range of the 
material. It is also necessary that the three negatives be developed 
to the same contrast, although slight variations are always permis- 
sible. If the same panchromatic material is used for all three nega- 
tives, it will be found that the blue-filter negative always shows a 
much lower contrast than either the green- or red-filter negatives, for 
the same time of development. Therefore, this 'particular negative 
must be developed for an appreciably longer time, which must be 
determined in practice by the regular sensitometric procedure. The 
red- and green-filter negatives are sufficiently close together, and do 
not usually require any correction. Information about the proper 
development can also be readily obtained from the manufacturers of 
the photographic negative material that is being used. 

Practice has also shown the desirability of including in the subject 
a so-called neutral-gray wedge. By means of the neutral wedge, we 
can determine whether the three negatives are uniformly exposed and 
developed to the same contrast. Furthermore, by its use we can 
determine with extreme accuracy the printing ratio. It is seldom 
possible to obtain three accurately balanced negatives requiring the 

Oct , 19.37] COLOR STILLS 407 

same printing light, and therefore the measurement of the transmis- 
sion value of the corresponding steps of the gray wedge will obviate 
many trial printing exposures afterward. In this connection a 
very valuable instrument for the color worker is a transmission 
densitometer now commercially obtainable from the Eastman Kodak 
Company. The same densitometer can al^o be obtained in a form 
that permits measurement of the reflection from paper surfaces so 
that further check of the exposure of the gray wedge on paper may be 
made after printing. This, of course, applies to those color printing 
methods that require the use of bromide positives as intermediate 

Another important point to be kept in mind in color photography 
is to avoid extreme light contrast, for several reasons. If, for in- 
stance, we should wish to cover the full range represented by the 
scale of the negative material, it would be necessary that the three 
negatives be extremely accurately exposed, otherwise color tones at 
the extreme ends of the scale would depart appreciably from the true 
values. This is readily understood when we consider that the 
characteristic of the photographic material consists essentially of 
three regions: (a) the straight-line portion, which is the useful por- 
tion, and in which a linear relation exists between the light value of 
the subject and the light value of the photographic reproduction; 
(6) the underexposure region ; and (c) overexposure region, in which 
no linear relation exists. If the light range of the subjects is moderate 
and covers only a part of the straight-line region, it is also obvious 
that the three negatives can depart slightly from each other in the 
value of the gray wedge, and the only adjustment necessary for correct 
tone reproduction will be a proper change of printing light. If, on 
the other hand, the light range is very great and the negatives are 
out of balance with respect to the gray wedge, we shall find that some 
of the color tones in some of the negatives will be in the region of 
overexposure, and in the other negatives in the region of under- 
exposure. Adjustment of the printing light under those conditions 
will not permit acceptable color reproduction, and we can hope to 
obtain only a fair reproduction of the middle tones. 

Only after considerable experience in the production of color- 
separation negatives and in printing methods can one attempt to 
extend the light range. 4 ' 5 

It must be also kept in mind that if color photographs are to be 
reproduced by photomechanical printing processes, the light range 

408 O. O. CECCARINI [J. S. M. P. E. 

available with the usual printing inks is appreciably less than the 
range attainable with bromide and carbon prints. For instance, a 
platinum paper might have a light range of 80 to 1, while the range 
of printing inks is well known to be a fraction of that. It would be 
therefore impracticable to attempt to reproduce a subject with ex- 
cessive light contrast. 

Having obtained a correct set of the color-separation negatives 
with the gray wedge included, and assuming that the contrast of the 
three negatives is also uniform and within practical values, we are 
required to produce a color proof on paper. For this purpose several 
methods are available. We might use the method of three super- 
imposed carbon prints ; we might use the method involving the trans- 
fer of transparent aniline dyes; we might produce the three constitu- 
ent images by chemical toning methods to be afterward super- 
imposed on paper; or we might combine some of these methods to- 

Today, unquestionably, the color print made by a carbon process 
is the most beautiful and the most permanent, but it is also probably 
the most difficult to make. However, in view of the exceptional re- 
sults that can be obtained by it, a description of it will be given, 
although information can be obtained from the makers of the carbon 
tissues, 6 and from many text-books listed in the attached bibliography. 
The carbon prints can be produced in two ways : We can make them 
by the method of enlarged negatives to be printed afterward by con- 
tact upon carbon tissues of appropriate colors, sensitized in a mixture 
of bicromate of potassium or ammonium ; or we might adopt the more 
modern method of making enlargements upon suitable bromide papers 
and then allowing a chemical reaction to take place between the bro- 
mide paper and the carbon tissue, after the tissue is suitably sensitized 
in chemical baths containing bleaching and hardening agents. The 
latter method is commonly known as Carbro method. Since the 
procedure is identical in the two methods after the tissues have been 
reacted upon by the exposing light through the negative or by the 
tanning action of the bleaching and hardening agents, we shall ex- 
amine the Carbro method only. 

From the three-color separation negatives three bromides, either 
by contact or enlargement, are made with an exposure in accordance 
with the transmission readings of the gray wedge, care being exer- 
cised that during the enlarging the size is- accurately maintained. 
Unless one is absolutely sure of the uniformity of the illumination of 

Oct., 1937] COLOR STILLS 400 

the projection apparatus, the negatives must be placed in identical 
position in the negative carrier so that any lack of uniformity of light 
will affect all three negatives to the same degree. The most suitable 
bromide paper for this work is one having a soft or unhardened emul- 
sion and must be rich in silver content. Suppliers of carbon tissues 
list the most convenient types of bromide papers, and since different 
papers require variations in technic and manipulation, one should 
endeavor to specialize in one type only. This can not be regarded as 
a limitation because the bromide paper serves only as an intermediate 
step, and the degree of control available in the form of bromide de- 
velopment and the compounding of sensitizing solutions for the tissues 
will be found ample for requirements demanded by negatives of 
average quality. The quality of bromide print should be of the 
highest value, without fogging of the highlights and without exces- 
sively deep shadows. It is also very important to develop the three 
bromides to the same contrast, and in order to facilitate this step it 
is desirable to use a large quantity of developer if the prints are 
made in succession, or to develop each bromide separately in a small 
quantity of fresh developer. In any case, the temperature of the 
developer should be kept the same because the activity of the 
developer is materially affected by its temperature. 

With regard to the fixing bath, although many persons recommend 
plain hypo rendered acid with sodium bisulfite, or potassium meta- 
bisulfite, the writer has found that the use of a plain hypo without 
any acid is ordinarily to be preferred unless one is willing to pay ex- 
treme attention to the degree of washing that has to follow. Any 
acidity of the emulsion of the paper affects the behavior of the Carbro 
solution to a very marked degree. It is, therefore, desirable to avoid 
the acid and discard the hypo after the bromides have been properly 
fixed. The condition of the wash water might also affect the behavior 
of the Carbro solutions, particularly if lime or other chemical sub- 
stances are present to an appreciable extent. Many Carbro workers 
treat the bromide prints in a solution of diluted acetic acid (half 
ounce glacial acetic acid in twenty-five ounces water) for about three 
or four minutes followed by eight or ten minutes of wash of running 
water. The writer finds that under these conditions the amount of 
acetic acid retained by the bromides is too great and the Carbros thin. 
A better procedure is to use a much smaller amount of acid, l /4 per 
cent solution of acetic acid, for instance, for exactly four minutes 
followed by a wash of running water again for four minutes, after 

410 O. O. CECCARINI [J.S. M. P. K. 

which the bromide papers can be slightly drained and placed in a tray 
with a small amount of distilled water until used. 

It will be found that if this procedure is followed, the quality of 
the Carbro image will be of normal strength, as if no acid bath had been 
used, and with none of the highlight irregularities and defects caused 
by chemical impurities of the wash water. 

The Carbro solutions ordinarily consist of bleaching agents as a first 
bath and controlling agents as a second bath. The compounding and 
use of the two baths are amply described in the pamphlet on trichrome 
Carbro printing by the makers of carbon tissues. The writer again 
finds it more expedient and convenient to use the combined or single 
bath procedure. The single-bath method permits much more even 
results, and it is not as critical with respect to time as the two-solution 
method. With the two-solution method the time of immersion in the 
second bath controls the degree of contrast of the resulting print, 
while with the combined or single bath the variation of time of im- 
mersion has very little effect upon contrast. This can hardly be 
called an objection, as all the bromides are supposed to be of equal 
contrast and suitable quality. A change of contrast, however, can 
be readily attained by first compounding the normal bath for the 
tissue or tissues requiring normal contrast, then adding to the bath 
a small amount of controlling solution for the other tissue or tissues 
requiring less contrast. In other words, the procedure is to leave 
for last the tissue that must be made softer, because a chemical con- 
trolling agent can be added to, but not subtracted from the bath. 

In order properly to produce a desired change of contrast the worker 
must know the quality of contrast attainable with definite quantities 
of controlling agents. This is readily determined by making several 
identical graded strips on the bromide paper, and then treating a 
black tissue with the single bath of different composition, a record 
of which must be carefully kept. Upon developing these various 
tissues a measurement of the resulting contrast can be readily made 
by means of the reflection densitometer. It is also possible to ex- 
press in a tabulated form or graphically, the variation of contrast 
in terms of the controlling agents present in the single bath, so that 
in future any desired variation of contrast can be readily interpolated 
from the record on hand. If a reflection densitometer is not available 
for measuring the graded carbon strips, the transmission densitometer 
can be used for the purpose by developing the graded carbon strip 
on thin transparent celluloid. If this procedure is adopted one must 

Oct., 1937] COLOR STILLS 411 

bear in mind that the apparent contrast of -a graded strip by trans- 
mitted light is approximately one-half its value by reflected light. 
For a more accurate relation between transmission and reflection 
densities one might refer to an article by F. F. Renwick in the Photo- 
graphic Journal (Jan., 1937). 

The writer finds also that except in the case of prints smaller than 
8 by 10 inches, the use of an automatic squeegee to produce intimate 
and uniform contact between the bromide and the carbon tissue is of 
extreme importance. Such squeegees are not ordinarily available 
commercially, but can be readily assembled by anyone and do not 
present any great difficulty. However, the required roller pressure 
must be adjustable, and a few experiments are necessary before the 
right degree of pressure is arrived at. It will be found, ordinarily, 
that too much pressure will tend to produce irregular patches and the 
pressure must be gradually reduced until any trace of irregularity is 
unnoticeable. A critical test for the pressure can be readily carried 
out by exposing a bromide paper very lightly and uniformly, and 
using the blue carbon tissue for tests, as with this color any irregu- 
larities throughout the surface that would readily pass unnoticed with 
red and yellow tissues are immediately noticeable. In this respect it 
will be found that the single-bath method is less critical to the 
squeegee pressure. 

It will also be found that the use of a combined or single-bath has 
been recommended in two different ways. One method consists of a 
preliminary bathing of the tissue in plain water, while the other 
consists in placing the tissue in the sensitizing bath without pre- 
liminary treatment. The latter method is to be preferred from the 
standpoint of evenness in connection with the automatic squeegee. 

The next printing process that has attained considerable popularity 
during the last year or two is the relief or imbibition process. This 
process is exemplified by the Eastman wash-off relief, and the very 
complete and accurate instructions issued by the Eastman Kodak 
Company make it possible to produce very acceptable prints on paper 
with a relatively moderate background of experience. 7 The sequence 
of the various operations is very carefully outlined in the instructions, 
and unless one departs deliberately from the instructions there is very 
little chance of going wrong. There is, therefore, very little that one 
can add to it. 

The color prints made by this method consist of extremely trans- 
parent dyes, and the results are therefore very luminous. They lack, 

412 O. O. CECCARINI [J. S. M. P. E. 

however, the peculiar sensation of depth that is characteristic of 
the prints made by the Carbro process. Since acid dyes are used for 
the process the color prints are also undoubtedly quite permanent, 
although perhaps not as much so as Carbro prints. 

Instead of using the Eastman wash-off relief film one could also use 
a special carbon tissue for the purpose of producing the relief image 
to be subsequently used as a matrix. When this carbon tissue is 
used for the purpose, the process assumes the trade name of Dyebro, 
material for which is manufactured by the Autotype Company in 

Obviously, in order to produce the matrices by means of the carbon 
tissue one must make bromide prints as the first step by substantially 
the same procedure as described previously for Carbro. An alter- 
native variation of the Dyebro process consists in toning chemically 
the bromide print obtained from a red-filter negative by means of an 
iron blue toner, and subsequently transferring on to this toned bro- 
mide the magenta and the yellow color by means of the carbon tissue 

In carrying out the process in this form one has to contend with the 
proper determination of the effective contrast of the toned blue image 
with respect to the effective contrast of the magenta and yellow dye 
images transferred on to it. The correct values of the contrast must 
be arrived at empirically. It is also necessary to determine empiri- 
cally the law of contrast variation for the three images in order to be 
able to make the required changes if necessity for changing the con- 
trast should arise. From the standpoint of simplicity and uniformity 
the wash-off relief film supplied by the Eastman Kodak Company is 
certainly preferable. 

While the cost and the time required to produce the color print by 
the wash-off relief or imbibition method is approximately the same as 
by the Carbro method, additional prints of the same subject can be 
readily made by the imbibition process in a relatively short time. 
The only time required is the time necessary for the matrices to absorb 
the dye, and the time necessary for transferring it on paper, as these 
matrices can be used repeatedly for a very large number of prints. 
In the case of Carbro, of course, the time is the same for each print. 
With proper precautions the images obtained by dye transfer can be 
made to retain a sufficient degree of sharpness. 

The recent introduction of the complete toning process for the three 
constituent images under the trade-name of Chromatone 8 makes it 

Oct., 1937] COLOR STILLS 413 

possible to attain colored images of a degree of sharpness strictly 
identical with that of a bromide print. The Chromatone process is 
also fully covered by careful instructions issued by the manufacturers, 
and by this method also it is possible to attain very satisfactory color 
prints on paper with no other knowledge than the ordinary photo- 
graphic experience that anyone can readily acquire. The constituent 
colors of the Chromatone process are also fairly close to the ideal com- 
plementary colors and, therefore, satisfactory color-balance and 
intermediate tones are readily obtainable. 

The three-toned images consist of a regular gelatin emulsion sup- 
ported on thin layers of collodion. The chief difficulty with the col- 
lodion support is that when it is mounted upon the final paper support 
and dried it tends to curl inward, and must be carefully mounted. 
Also, the glossy appearance of the collodion surface might not be as 
artistic as an ordinary gelatin surface. In this case, however, it is 
possible to assemble the images with the gelatin surface uppermost, 
which, of course, requires that the printing be done through reversed 
negatives. The blue and magenta images obtained by chemical 
toning are not very transparent, and the resulting prints are therefore 
not as brilliant as prints made by the imbibition method or by the 
Carbro process. Nevertheless, all in all, the Chromatone method can 
be considered quite a satisfactory procedure to produce quick proofs 
from color-separation negatives. The time required for making each 
print by this process is also approximately the same as for the Carbro 
and imbibition methods, and, as with the Carbro, the same time is 
required for each successive print, so that if several prints are required 
the imbibition method is again to be preferred. Very little is known 
about the permanency of the Chromatone images. 

Another process that is very little practiced, but which is never- 
theless capable of excellent results, consists in making prints on posi- 
tive films and then treating the positives by some of the well known 
mordanting processes. The copper mordant is usually the most re- 
liable. The dyes to be used with the mordant process are obviously 
basic dyes, which unfortunately are not as fast to light as acid dyes 
and, therefore, color prints made by this method should not be unduly 
exposed to sunlight. Assembling the mordanted images can be car- 
ried out by the method suggested by Namias many years back, 9 
which consists in cementing the yellow positive to a final paper sup- 
port, and, when dry, removing the celluloid base of the film by dis- 
solving it in acetone, thus leaving only the original gelatin emulsion 

414 O. O. CECCARINI [J. S. M. P. E. 

formerly carried by the film base. The red image is applied next, 
also preferably with a gelatin cement, and when dry the celluloid 
support also is removed by treatment with acetone. The blue posi- 
tive is assembled in a similar manner. In this way the three-color 
positives are assembled with only the gelatin layers between them, 
and the quality and sharpness of color images attainable by this 
method are indeed surprising. The time required for producing the 
complete picture is comparable with that of the processes so far 

It is possible to obtain extremely brilliant dye mordant images also 
by transferring the basic dyes to a final support coated with collodion 
emulsion, since collodion has a great affinity for basic dyes. This 
method was suggested by R. von Arx. 10 The same author suggested 
also transferring mordanted dyes to a final support containing a 
mordant of a more powerful nature than the one by which the dye 
images are made. 

There are other processes in commercial use today and which to 
some extent are closely related to those already described. Among 
them might be mentioned the Duxochrome process. This process 
resembles very much the Deck's color-sheet process, which was intro- 
duced commercially about 1923 and exploited by the American Raylo 
Corporation. These sheets carry in suspension in the gelatin layer 
the necessary dyes, together with the silver bromide emulsion. The 
exposure of the sheets is carried out as with ordinary enlarging paper, 
and after development by means of a tanning developer, the gelatin 
emulsion is washed off in the hot water, thus producing a relief gela- 
tin image. After the developed silver images are bleached the re- 
maining colored images in relief are transferred to a gelatin-coated 
final support. 11 This method is possibly slightly speedier than any of 
the methods so far described, but the cost of the material is appreciably 
higher, and the quality of the image does not surpass that attainable 
with the Carbro process, although it might be less difficult from the 
technical standpoint. 

The color technician of a motion picture studio is seldom required 
to produce more than one proof on paper, and it is therefore very 
difficult to suggest the most appropriate means for producing this 
proof, as the time involved for a single print is substantially the same 
for nearly all the processes mentioned so far. In choosing a method, 
one therefore must be guided by the precision and the standard of 
quality demanded, and by the ability of the personnel who have to 

Oct., 1937] COLOR STILLS 415 

carry through the actual manual operations. It is conceivable, how- 
ever, that cases may exist for which a fairly large number of prints of 
the same subject might be desirable; several dozen, for instance, or a 
few hundred. In such case to produce the prints by the chemical 
processes so far described is out of the question, and the initial cost 
demanded by setting up printing matrices by any one of the photo- 
mechanical processes is unreasonably high. In such cases it seems 
that the Collotype method might be rightfully called into play. 12 

This method, although substantially a photomechanical process, is 
very closely related to the Bromoil 13 process used by many pictorial- 
ists. The production of Collotype printing plates is substantially 
an easy matter, and suitable film can be readily obtained commercially 
today. Since this method relies upon the property of the bichro- 
mated gelatin to reticulate when differentially hardened by ex- 
posure to light and subsequently treated with a mixture of water and 
glycerin, the resulting images are extremely beautiful and delicate 
in details, and resemble very closely the quality of a photographic 
print. Color reproductions by this method are extremely beautiful, 
and it is possible to obtain as many as a thousand pulls from each set 
of Collotype plates. The method could, therefore, be readily sug- 
gested for the production of portraits of outstanding personalities, 
or prints for lobby displays, or in any case where the demand does 
not exceed a few hundred samples. 

It is conceivable also that the allied Bromoil process could be used 
instead of Collotype for a limited number of prints (a dozen, for 
instance), in which case, however, the matrices should be inked by a 
mechanically operated automatic brush in order to produce a rapid 
and uniform inking. The general control is done strictly by the 
moisture content of the gelatin. The use of a bromide paper specially 
manufactured for Bromoil is not necessary, but, instead, a regular 
positive film can be very conveniently employed. The film has the 
advantage of retaining its size and permitting accurate registration. 


1 "Repeating Back for Color Exposures," Brit. J. Phot. Color Supp., 79, 
(June 3, 1932), p. 22. 

2 STRONG, J.: "On a Method of Decreasing the Reflection from Non-Metallic 
Substances," /. Opt. Soc. Amer., 26 (Jan., 1936), p. 73. 

3 U. S. Ordnance Department Document No. 2037, p. 77. 

4 POTTER, R. S. : "Methods of Making Three-Color Separation Negatives," 
Defender Photo Supply Co., Rochester, N. Y., (1937). 


5 "Color Separation Negatives," Brit. J. Phot. Almanac (1937). 
4 "Trichrome Printing by the Autotype Carbro Process" (obtainable in 
U. S. A. through George Murphy, Inc., New York, N. Y.). 

7 "Color Printing with Eastman Wash-Off Relief Film," Eastman Kodak Co., 
Rochester, N. Y. 

8 "The Chromatone Process," Defender Photo Supply Co., Rochester, N. Y. 

9 NAMIAS, R.: "La Fotografia a Colori," // Progresso Fotografico (Fifth Ed.. 
1930), Milan, Italy. 

10 VON ARX, R.: "The Mordant Dye Printing Process" (Proceedings of the 
Seventh International Congress of Photography, London, 1928), Heffer & Sons 
(1929), Cambridge. 

11 WALL, E. J.: "Practical Color Photography," Amer. Phot. Pub. Co., Boston, 

14 NAMIAS, R.: "La Collografia," // Progresso Fotografico (1925), Milan, 

PFUND, F.: "Handbuch der Modernen Reproduktions Technik," Verlag 
Von Klimsch & Co., II (1927), Frankfurt A.M. 

WILSON, T. A.: "The Practice of Collotype," Amer. Phot. Pub. Co. (1935) 
Boston, Mass. 

lf MAYER, E.: "Bromoil Printing and Transfer (in German)," Amer. Phot. 
Pub. Co. (1923), Boston, Mass. 


14 WALL, E. J. : "History of Color Photography," Amer. Phot. Pub. Co. (1925), 
Boston, Mass. 

15 WHEELER, O. : "Color Photography," I. Pitman & Son (1935), London. 

18 NEWENS, F. R.: "The Technic of Three-Color Photography," Blackie & 
Sons, Ltd. (1936), London. 

"HUBL, A.: "Three-Color Photography," A. W. Penrose & Co. (1904), 

18 DUNN, C. E.: "Natural Color Processes," Amer. Phot. Pub. Co. (1936), 
Boston, Mass. 

19 KLEIN, A.: "Color Cinematography," Amer. Phot. Pub. Co. (1936), Boston, 



MR. SOLOW: I am sure that Mr. Ceccarini would be interested in knowing 
that the Collotype process is used extensively hi this country for the production 
of three-color lobby displays. The process has been adapted to high-speed 
rotary presses by the use of bichromated gelatin coated on thin sheets of alumi- 
num, and prints as large as 40 by 60 inches are possible. 

MR. CECCARINI: By Collotype in this particular case I mean the "typical 
small installation" employing printing plates of bichromated gelatin without the 
use of any photomechanical process screen. The reticulation of the gelatin coat- 
ing is produced by treatment with a mixture of water and glycerin. 



Summary. Computations and measurements show that the background noise of 
film can be interpreted as the superposition of two types of noise: surface noise, and 
grain noise. The surface noise power decreases with the square of specular trans- 
mission; the grain noise power reaches a maximum at 50 per cent transmission. 
Accordingly, it is found that under conditions of variable-width recording surface 
noise is predominant; for variable-density recording, grain noise is the main factor. 
The average area of the grains or grain clusters can be calculated from the signal-to- 
noise ratio; their average volume from the total weight of silver per square centimeter 
at a given density; their average thickness from the quotient of volume and area. 
For equal grain sizes, surface exposure such as obtained by ultraviolet illumina- 
tion is definitely noisier than penetrating exposure. 

Upon the basis of random three-dimensional distribution of sensitized grains and 
of the quantum theoretical findings of previous investigators, the shapes of H&D 
curves were calculated. The assumption that a halide grain is sensitized by a single 
photon leads to a toe shape that is more rounded than is found in practice. The 
actual shape of the characteristic from toe to shoulder is accounted for by the assump- 
tion that it takes two photons to sensitize a silver halide grain. It is expressed by the 

n > r c e i - e ~* , i 

D = y- -<" - e~ - I - dx \ 

In <p [_ J er x 

in which r represents the translucence of the unexposed emulsion to the actinic light. 
The experimental fact that the straight portions of H&D curves obtained from the 
same emulsion at various gammas originate from a single point which is depressed by 
bromide content is explainable by taking into account the fact that the emulsion con- 
tains silver halide grains of more than one size and speed. 

Important inventions and new technical processes are usually intro- 
duced as new "arts" in the language of the patent law, as well as in 
fact. The word implies that the details of the process are not gen- 
erally known and require a special skill or instinct for their operation. 
As practical knowledge is gained, the new process becomes a "craft." 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received 
May 20, 1937. 

** Electrical Research Products, Inc., New York, N. Y. 


418 W. J. ALBERSHEIM [J. S. M. P. E. 

This is the stage at which the trained foreman, with his long years 
of shop experience, is indispensable. A large number of quantitative 
rules and secret processes is being worked out; but they are mostly 
rules of thumb derived from practical results without understanding 
of the inner causes. Finally the process becomes a "science," the 
many quantitative relations are analyzed and are found to be con- 
sequences or special cases of a few basic principles; thus, technical 
results and possible improvements become predictable and subject 
to engineering. 

In the motion picture film industry, the same development is taking 
place. The early publications in the pioneering age dealt largely 
in observational qualitative terms. Large-scale properties of the 
emulsion were given vague names such as "speed" and "contrast," 
and the small-scale properties of film grains were described as "boil- 
ing" and "graininess." The density characteristic was roughly 
divided into the "toe," "straight line," and "shoulder" regions. 

The advent of sound-film recording, with its high and technically 
well defined requirements, brought about more or less rigid quanti- 
tative definitions of film characteristics. The sound engineer thinks 
of the properties of the film emulsions in functional terms. The 
curvature of the density characteristic determines amplitude dis- 
tortion, harmonic overtones, cross-modulation, etc. The micro- 
scopic qualities of the emulsion and of the film base become audible 
as high-frequency losses and as background noise. All these effects 
have been quantitatively measured by the various companies active 
in the industry and have resulted in a number of jealously guarded 
secret processes on the side of the film manufacturers, and, on the 
side of the film users, in various methods of sound-film recording and 
reproducing attempting to utilize the given film characteristics in 
the most efficient manner. 

If we now attempt to correlate this abundant practical informa- 
tion, we find that the directly measured and technically important 
qualities, such as density, noise-level and noise frequency spectrum, 
are large-scale properties; and yet we know, by microscopic inspec- 
tion, that they are caused by the additive action of millions of small 
silver grains. We are dealing with a problem similar to that solved 
by Clerk Maxwell, who interpreted all the large-scale properties of 
gases, such as pressure, heat expansion, entropy, and viscosity, as the 
combined effect of countless molecules in random motion. 

We need not concern ourselves with the exact shape and size of 


the individual film grain but with the resultant effects of their sum. 
In other words, all the observed properties of film must be explain- 
able, and perhaps new relations may be found, by applying statis- 
tical calculation to the emulsion of silver grains. The present paper 
aims to give some of these statistics. 


Our first problem is to decide what degree of statistical freedom 
to apply: do the silver grains form a 2-dimensional array like the 
small stones in a mosaic picture, or a 3-dimensional array like the 
berries in a flat dish of huckleberry pie? Both these types of ar- 
rangement may be approximated in reality, depending upon the 
intensity and penetrating power of light and development. Let 
us derive the laws for both types of image and compare them with 
experimental facts. 

We begin with the following simplifying idealizations, part of 
which we may drop as we go along: (7) The image is composed of 
silver grains uniform in size and shape, completely opaque, and 
large compared to the wavelength of light; (2) the light falling into 
the photoelectric cell is completely specular, so that we may neglect 
all diffraction effects. 

Case 1. Two-Dimensional Array (Surface Image}. The assump- 
tion of a 2-dimensional array is expressed in the relation:* 

N-M _ M Ma 

N N A 

Regarding the slit area as a mosaic of M' black "grains" and N M' 
white "gaps" we find that the probability of finding a given mosaic 
figure consisting of M' grains equals 

(M\ M '/N M\ N ~ M> 
f ) (^-^) = (1 - V' T*-*" (2) 

The number of possible permutations without change of M' equals 


^ (M > M' l(N - M') ! 

and therefore the total probability of finding M' grains 

M*"(N - M)"-*' JV! 
"' : M' l(N - M') \N N 


* See list of symbols, p. 444. 

420 W. J. ALBERSHEIM [J. S. M. P. E. 

The probability of finding M' + 1 grains equals 

M*'+i(N - M)x-x'- l Nl 
M ' +l (M' + 1) ! (N - M' - 1)1 NX 


Pfr'+i) _ M(N - M') = N- M' . M_ . M' 


P(M) (N - M)(M' + 1) N - M M' M' + 1 

=ln(l - _^_-^ - In ( 1 + ^) 

- In ( 1 + i) (7) 

Since the number of grains is very great and the variations in number 
relatively small one may approximate: 

d In P(M)' d In P( M Y 8M _ SM[ N 8M 

AM' d8M N - M M = (N - Af)M 

by integration one finds 


in which P a has the value of equation 4. From equation 1 one 
finds that 

5M = -N(8T) (11) 


This is a typical probability function, from which one finds 

0.477 2T - 0.675 - ~ = 0.675T -. 

. Three-Dimensional Array (Depth Penetration of Image). 
By a reasoning identical with that of case 1 we find again 

M = 0.675^^ =0.675^(1- |)M 

From this probable deviation.of grain number one finds the density 
or transmission deviations by the following reasoning: Imagine 


that the emulsion, which may have a thickness of y cm., is divided 
into a great number of extremely thin slices dy. Each slice is thick 
enough to accommodate only one grain layer. The slicing knife is 
supposed to be slightly blunted so that no grain is cut but is pushed 
into the next lower or higher slice. Since the grains are distributed 
at random, one may regard each slice as a diffuse absorption screen. 
The density of the entire emulsion is then the sum of all the single- 
slice densities: 

D = -s Di (is) 

or, in the limit 

D = f y dD/dy.dy (16) 


Each layer is subject to two-dimensional reasoning, and, ac- 
cordingly : 

1 - dT = ^dM (17) 

d D e = -In dT - 1 - dT = -. dM (18) 


D e = f dD. = \M = Q (19) 

IAD,! = 

= -. AM 

AF = TabM = 0.675 ** f - m > a * M 

_ M ja 3 M 
~~N ' A/"^" 


I TUT 1 n 

= 0.675 

The fraction M/N now means the spatial silver content of the 
emulsion in cm* Ag per cm 3 emulsion, which is a very small fraction. 
Hence one can approximate 

Ar = 0.675 T-J^ . V2i3~D = 1.022 T-Jj ^/D~ (23) 

In comparing equations 13 and 23 one may first consider the proper- 
ties that they have in common : 

(1) The probable deviation of the transmission is inverse to the 
square-root of the scanning area. This means that the ratio of 
noise-power to the power of a fully modulated low-frequency signal 
decreases inversely to the slit area. 

422 W. J. ALBERSHEIM [J. S. M. P. E. 

(1.1} Doubling the track width must increase the volume range 

3 db. 

(1.2) Doubling the slit spacing must likewise decrease the relative 
noise-power 3 db.; but for a given film-scanning speed it 
also cuts the frequency range in half. Hence it is deduced 
that the noise-power must be evenly spread over the entire 
frequency band; provided that each cycle of the highest 
scanned frequency contains a large number of grains. 

Both these deductions have been verified by engineers of 
the Bell System for frequencies over a few hundred cps.; 
that is, for wavelengths smaller than l / i6 inch or so. 

Low frequencies are subject to disturbances that are not 
random in three dimensions and partly not random at all. 
Such disturbances are, for instance, the minute "ripples" 
hi the flow of emulsion during the coating process and the 
ever-present sprocket-hole modulation of 96 cps. 
(2) The probable deviation (or noise amplitude) increases with 
the square root of the grain area. 

(5) The probable deviation due to silver grains vanishes for com- 
pletely transparent film as well as for completely opaque film. 

This result is logical, but it is known from experiment that even un- 
exposed and undeveloped film from which all silver has been dis- 
solved by the fixing process produces a considerable amount of noise 
due to inhomogenities of surfaces, emulsion, and film base. Fre- 
quently these noises are lumped under the name of "surface noise." 

One must regard this surface-effect as an entirely separate source 
of noise which contributes its own density as well as density deviation. 
Since the deviations are of a random nature they have to be combined 
by root-mean-square addition. One may write: 

A*Z> = A*>. + AW = K + &*D 9 (24) 

Consider next the differences between the two cases, in order to 
decide which corresponds more closely to actual conditions. 

(4) Relation of silver weight to density. For Case 1 one finds 
from equation 1: 

M, - tf(i - r) (25) 

and in view of 

A. ---? (26) 


A tl = ^ (1 - T) ' (27) 

This implies that for high densities the silver content approaches 
the fixed maximum value Vd/a. 
For Case 2 one finds from equation 19 

M* = D.N (28) 


_ V P D. _ V P D 
A <* ~ IT ~ 23~a 

Equation 29 indicates that the silver weight is directly propor- 
tional to density. Investigations conducted at the Eastman Kodak 
Laboratories 1 confirm this relation for normal types of emulsion 
and exposure. This is weighty evidence in favor of the three- 
dimensional statistics. And yet there are some recording methods 
in which an effort is made to enforce surface images for the sake of 
better high-frequency definition. Several years ago such tests 
were made with the use of dyes in the emulsion that strongly absorb 
the photographically active rays. 

Another recording method illuminates the film with light of short 
wavelength, which is highly attenuated by the standard motion 
picture film emulsions. In order to find out how closely the second 
method approaches the ideal two-dimensional case, the ERPI 
Engineering Department recorded variable-density frequency test- 
films, first in the normal manner, then through filters that limited 
the light to the violet end of the spectrum, and compared frequency 
characteristics and volume ranges. 

No difference in frequency characteristic was found; however, 
this result is not conclusive, since the optical system was corrected 
for normal incandescent light and was refocused but not modified 
for the filtered light. 

The result did show, however, a 4-db. increase of background noise 
in the "violet" recording which we shall compare with the theoretical 
volume range. 

Volume range is defined as the difference in db. between the ground- 
noise power and the power of a sine wave at overload level. For 
densities smaller than 0.3 the volume range equals : 

V, = 20 log n e) (**) 


For densities larger than 0.3 it is 

[J. S. M. P. E. 


Applying this relation to 13 and neglecting the surface-noise, one finds 
for the two-dimensional case 

~ (31a) 


+ 10 log y + 10 log 

V Kb = 3.4 + 10 log - - 10 log ( 1 


FIG. 1. Computed relative volume ranges. 

Applying 30 to equation 23, and again neglecting the surface-noise, 
one finds 

- 10 log D (32a) 

V Ru = -0.2 + 10 log +20 log 

V Rb -- 0.2 + 10 log (\ - 10 log D 

Omitting the constant term 10 log (A /a) these volume ranges have 
been plotted in Fig. 1. It is seen that regardless of the type of ex- 
posure the maximum volume range is obtained at the density 0.3. Un- 
fortunately, this optimum is difficult to realize due to the curvature 
of the toe characteristic. 






426 W. J. ALBERSHEIM [J. S. M. p. E. 

At specular densities near 0.7 which are normal for variable- 
density negatives, the calculated volume range of the surface exposure 
is about 4 db. lower than that of the depth exposure, a result that more 
than offsets any possible improvement in high-frequency response. 

This agreement of theory and experiment strengthens the belief 
that surface exposure may be approached by deliberate measures, 
but that the normal type of sound-film exposure can be classed as 
depth exposure within the meaning of our theory. 

Our experiments with regard to the relative noise-level of surface 
and depth exposures were conducted with the variable-density method. 
The variable-width method works with markedly different condi- 
tions. In the ideal case, one-half of the negative track is entirely 
unexposed aird therefore grainless, the other half highly overexposed 
and therefore practically opaque. In the unexposed half of the track 
the actual noise is "surface noise," which is unaffected by the nature 
of the exposure. In the dark portion, equation 13 indicates that while 
the noise power is higher for surface exposure than for depth exposure, 
it approaches zero for zero transmission. 

The trouble is only that with a single layer of grains it is difficult 
to approach zero transmission. Our "two-dimensional statistics" 
were based upon the assumption that the mosaic of film grains 
can completely cover the emulsion. This would be possible if all 
the grains were rectangles, or triangles of uniform size and shape. 
Actually they are crystals of irregular size and shape which might be 
visualized as a mixture of microscopic poker chips, domino bars, 
triangles, etc. Obviously one can not cover an area by a single 
layer of such grains without leaving irregular gaps which are decided 
deviations from the desired blackness. 

The more one approaches ideal surface exposure the more noise 
will be transmitted by the dark portion of the negative track. In 
the print these gaps will be shown as black dots on the light side of 
the positive, and if the print, too, is a surface image, its dark side 
will have new gaps which further increase the noise. 

As a final check of the three-dimensional theory, we derive the 
characteristic of noise-level versus specular density, taking into 
account the surface noise. We have 

D e = -A(lnr) = ~~ (33) 

Hence equation 24 can be transformed into 


(AT) 2 = r 2 . A 2 /),. + A*r,, 
In view of equation 23 one finds 

(AD 2 = r 2 [" A 2 !).. + 1.05^- D~\ 

Expressing the noise power level in db., one finds: 

L D = 10 log(AD 2 = L. - 20D X + 10 log D t 
In this equation 

L a = 0.2 + 10 log (^\ 


100 - A 2 D, 


Z>. - Z> + 6 - A 2 /), 

In Fig. 2 is seen the curve 

L 20D + 10 log 




Comparing equations 36 and 37 it is seen that L corresponds to 
a shift parallel to the ordinate axis fixing the absolute noise-level, 

FIG. 4. Film noise tests. 

and the substitution of D x for D corresponds to a shift along the 
abscissa, determined by the ratio of ground-noise to maximum 

Since 36 is the most general case, it is claimed by the theory that 
any experimental curve of ground-noise level versus specular density 


can be made to coincide with the curve of Fig. 2 by a parallel shift 
without tilting. Figs. 3 and 4 show superposition of function 37 
on tests made with Eastman emulsions 1301 and 1359, respectively. 
The agreement is very good and well within the limits of observa- 
tional errors. The only region where systematic differences of about 
1 db. seem to occur is at extremely low densities, in the "toe" region 
of the H&D curve. This is partly due to the fact that this region 
approaches surface exposure, partly to the fact that the grains are 
not all of one size. At low exposures the largest grains have the 
greatest probability of being hit by photons and thus increase the 
average grain size, as discussed below in the section on Bromide 

In view of the fact that the low-frequency noises are not random 
effects, the noise of the test-films shown in Figs. 3 and 4 was measured 
with a transmission circuit including a one-section, 500-cycle low- 
pass filter. 

By measuring the level difference between noise and a known 
amount of low-frequency modulation, one finds the absolute volume 
range and, therefrom, the grain area. 

The absolute levels are indicated on Figs. 3 and 4; they are subject 
to an error of 2 db. Based upon these figures the grain area of the 
high-gamma film, test No. 153, is computed in the following manner: 

From the amount of lateral shift necessary to superimpose Fig. 2 
upon the experimental curve: 

D z = D + 0.02 (38) 

From 36 one finds 

L = L D + 2QD, - 10 log D t (39) 

L = -55 + 20(0.735 + 0.03) - 10 log(0.735 + 0.03) = -38.5 (40) 

log j = 0.1 (L - 0.2 - 20X0.03) = -3.93 (41) 

Since the slit area was 

A = 80 square-mils, (42) 

a = 1.0 X lO- 8 sq. inches = 6.4 X 10~ cm. 1 (43) 

Assuming a round shape of the grain, one finds for the mean grain 

d = Vl-27o = 1.1 X 10- 4 in. = 2.9 X 10- 4 cm. = 2.9/u (44) 


For the low-gamma film, test No. 154, one finds in the same manner 

a = 3.04 X 10-o in. 2 = 2.0 X 10 ~ cm. 1 (45) 

d = 6.2 X 10~ s in. = 1.6 cm.~ = 1.6/t (46) 

The values 44 and 46 are of the right order of magnitude according 
to published figures and our own microscopic inspection. 

Having thus found the cross-sectional area and diameter of the 
grains, it is possible to find the average thickness (or depth) of the 
grain by weighing the amount of silver per unit surface. By defi- 
nition we have 

A a = Qy aP (47) 

In film No. 153 we found 

A, rf = 0.97 . D, = 1.21 

A e = 1.3 X 10~ 4 g cm 
p = 10.5 g cm~ 3 

Hence : 

= 2.3 X 1.3 X 10 ~* 
y ' " 1.21 X 10.5 

2.4 X 10^ s cm = 0.24/u (4Sb) 

The average thickness is about 10 tunes smaller than the average 
diameter. This indicates a flaky character of the film grains, caused 
conceivably by the stresses in flowing the emulsion on the base in a 
thin layer. 


Since the statistical viewpoint accounts well for the observation 
connected with film noise and grain size, we now apply it to 
the useful purpose of the film, that is to the formation of the 
latent photographic image and its development. The three-dimen- 
sional method of attack is applied again. It consists in subdividing 
the emulsion into a great number of thin layers, each of which con- 
tains sufficient grains to be subject to two-dimensional statistics and 
each of which acts as a diffusing screen on all others. 

We must now make some assumptions with regard to the photo- 
chemical mechanism by which a silver halide grain is modified to 
form the latent image. Our starting point is the application of 
quantum mechanics to photographic theory as set forth by J. H. 

430 W. J. ALBERSHEIM [J. S. M. P. E. 

Webb of the Eastman Kodak Research Laboratories in a recent paper. 2 
The general concept is about as follows: A halide grain, after 
cooking in the organic gelatin, has on its surface one or more "con- 
centration specks," which act as sensitizers. No matter where the 
grain is hit by a photon of light, there exists a certain probability 
that an electron may be knocked into an energy level at which it can 
freely travel through the grain as if the grain were metallic. It 
finds its way to the concentration speck, attaches itself to it, and 
thus becomes in some manner that is not yet fully explained, the 
starting point or "nucleus" for the action of the developer. Inci- 
dentally, there exists a (much smaller) probability that an electron 
already attached to the concentration speck is knocked loose again 
by a further photon impact. This photographic reversal effect is 
not taken into account in this paper because it is negligible at the 
exposures used for sound-film recording. Consider now a slice of 
emulsion of unit area and of the thickness dy. It contains h dy/ Y 
halide grains of a photographic "speed" or sensitivity 5. Let it be 
exposed to an illumination E y . How many grains will be activated 
by photons? 

According to the laws of mass action 

from which one finds 

dr v = ~ (1 - t -'B)dy (50) 

The illumination is a function of depth. Assuming that the 
turbidity and light absorption are uniform throughout the emulsion, 
one finds 


= - (52) 


dr v = p(l - e-V-)dy (55) 

and finally 


This integral can be simplified by introducing the translucence 


x = e- (55) 

and the "relative exposure" 

e = sEy (56) 

one finds 

(1 - t~")dx 

- H < 57 > 

This equation indicates the total number of activated grains per 
unit area. If one assumes that after development each activated 
grain is transformed into a silver grain of area a, one finds for the 
density, in view of equation 19, 

D, = -0.434, P * ~ * " dx (58) 

This, then, is the density-exposure function. 

When plotted upon a logarithmic exposure scale, it yields the 
H&D curve according to the "single hit" theory. The integral 
58 has no general solution, but it can be evaluated by series develop- 
ment. Correct and convergent for all exposures is the series 

r i - - 


dx = f(e) ** e H h (59) 

2.2! 3.3! 

which has been plotted as Fig. 5 and which solves the integral 58 in 
the following form: 

Series 59 becomes cumbersome for values of e greater than 4. 
Fortunately at these higher values the series can be approximated 
by the value 

e - -T^l +3^7 - + = In e + 0.592 (61) 

If (er) as well as e exceeds 4, Z>i approaches the end value 

, -0.434 ha M , / M 

i-'ico == : lln e \n\eT) \ 

In T 



For very small exposures, 

[J. S. M. P. E. 



.2 3 * .f .(. 1 

j \ II 

FIG. 5. Numerical values of integral 
f unction /(e). 


The gradient of the H&D curve is 

dD . ht 

[ e -T 

dloge 1 -Inr ' . -logr 1 ' 

This gradient reaches its maximum value T, when 


1 - 

r = - 


- r 

logr L 




Equation 69 gives a functional relation between F, D and T so that 
each can be calculated from the two others. For instance, if one 
knows F and D from an experimental H&D curve, one can find T 
from the function <p:(r), which has been evaluated in Fig. 6. Know- 
ing T and D one can plot the H&D curve from equation 63 and its 
series developments. 

This is shown for values of D and F that are normal in sound-film 
development in curve A of Fig. 7. It is seen that the general shape 
resembles an H&D curve but that the toe is too round. 

The difference between experimental and computed curves be- 
comes more apparent when density or transmission is plotted against 

FIG. 6. Translucency constant as a function of E maxi- 
mum density (single-hit). 

a linear exposure scale, as one usually does for the inspection of 
"toe records." This is shown in curve A of Fig. 8. The curve 
indicates for low exposures a linear decrease of transmission with 
exposure in accordance with equation 65. This toe shape disagrees 
with observation to such a degree that the "single hit" theory in 
the above form is unsatisfactory. 

Another fact that contradicts the relations deduced from the 
"single-hit" theory is the practice of astronomers and spectographers 
which consists in "prefogging" their plates for maximum sensitivity 
to faint illumination. From a differentiation of 63 with regard to 
e, one would find for the density-exposure gradient: 






[J. S. M. P. E. 

which has its maximum at zero exposures (unfogged plate!). 

The weight of evidence indicates that for very low illumination 
the density increases with the square of exposure. 

If one attempts to reconcile this experimental fact with the quan- 
tum mechanical viewpoint set forth by the above-quoted paper, 2 
one is led to the conclusion that a grain must be hit by at least two 
photons in order to become developable. 

It is not within the province of this analytical paper to find the 
photochemical mechanism that requires two mobile electrons for 
activation. One possible explanation might lie in the fact that in 

FIG. 7. Computed H&D curves. 

many compounds the halogenes act as if they had not only one 
chemical valence but were multivalent with a preference for the odd 
numbers. One might imagine some formula such as 

3AgCl + 2e~ = AgjCl + 2C1~ 

but we must leave this for investigators in the field of physical 
chemistry to decide. 

The "double-hit" hypothesis leads to formulas for density, F, 
etc., in a manner quite analogous to the single-hit calculations. In- 
stead of equation 49 above, one has two unknowns, dr and dg, and 
two equations: 

d(dr) = s (^ - dr\ dE (49) 


d(dg) = s(dr - dg)dE 
One finds 

dg = [1 - (1 + iE,) t -"*]j.dy 
In view of 52, 55, and 56: 



= r + 

lnrJ T 






S (CURVE A)| R6L) , TIVE EX posuRtx 
r 45e(CuRvEB)j k 

/ .2 .3 .4 

FIG. 8. Computed toe characteristics. 


g r + hLT (t T e ) 


Assuming again that the development transforms an activated silver 
halide crystal into a silver grain of the cross-sectional area a one finds 



^lnr ve 


= ^Tr \_<~' ~ *~' T + f (1 ~ 6 ~ l)d(ln - V 



[J. S. M. P. E. 

In evaluating this equation one may use either the previously 
given formulas for A and find separately the values for e~ e + e~ e ; 
or for small values of e, the combined series development. 


FIG. 9. Translucency constant as a function of gamma 
and maximum density (double-hit). 

which has the required square-law properties. The gradient of the 
H&D curve equals 


log r 



The maximum value of e is reached for 


One finds by combining equations 83 and 84, 

IT 2 

>, T/, 2r \ r=T / 21nr\ TZ^~| 

12=: ( 1 ~ - In T IT - ( 1 - )r 

log T L\ 1-7- / \ 1 - r) 



Again T, D m and r are inter-related and from T and D m one can 
ind T from function <pi(j) which has been plotted as Fig. 9. 
Knowing D and r one can plot the H&D curve from equation 79. 
Curve B of Fig. 7 shows the curve thus obtained for the same 
rallies of >_ and T as curve A. 

Curve B on Fig. 8 shows the toe characteristic of the same H&D 
urve. It has been compressed laterally by a factor of 4: 1 in order 
o reduce it to a convenient scale. 

It is apparent that curves B look like familiar H&D curves. As 
a matter of fact it has been possible to match closely all experimental 
sensitometric curves for high and low gammas that are reasonably 
free from fog. The accuracy of the match is commensurate with 
the accuracy of observation, and improves for experimental curves 
that are the averages of many well agitated sensitometer strips. 
The densities and gammas should be specular values. 

Fig. 10 shows as solid tines typical curves for high and low gamma 
developed in positive bath, measured several years ago; the visual 
diffuse values were accepted because the ratio of specular to diffuse 
gamma was not known for this particular case; it usually approxi- 
mates a constant value of about 1.35. The small circles show the 
calculated values; the closeness of agreement is evident. 

In analyzing equation 79 one sees that outside of D m , which de- 
termines the total height of the H&D curve, the only free parameter 
is the transhicence T. The smaller T, the longer the straight-tine 
portion of the H&D curve, as can be seen by inspection of equation 
S3. From this it may be concluded that a certain increase of tight 
absorption in recording and printing is beneficial as long as it does 
not approach the conditions of surface development, which reduces 
D m instead of increasing T. It would seem best to increase the ab- 
sorption by adding to the thirlcnpss of the emulsion. High density 
and contrast with low ground-noise should be obtained by a great 
number of small grains rather than by a few large grains. This, 
of course, will somewhat reduce the speed of the emulsion and, if 
thick emulsions are used, the picture detail. 



[J. S. M. P. E. 




The next test of the statistical method is its application to the 
theory of development and to the relations between characteristics 
produced from identical latent images by development for different 
lengths of time or in different developing agents. 

Equation 83 indicates that in the region in which e is much larger 
than one but er much smaller than one, the number of activated 
grains in the latent image increases in proportion to the logarithm 
of exposure. This, then, is the "straight-line portion of the H&D 
curve." It can be expressed by the approximate formula 

g = k(log e log i) (87) 

Our simplifying assumption of uniform halide grain size and compo- 
sition has the natural consequence that, regardless of nature and 
duration of the development, the developed grains are also closely 
grouped around a uniform value a, and hence 

D a = ka(log e - log *') = T( ) (log e - log) (88) 

If one permits a to change by varying the length of development, 
D a when plotted as a function of the logarithm of exposure, describes 
a family of straight lines originating in a common point on the 
exposure axis 

D = o, e = i (89) 

This family of lines is shown as Fig. 11 (a). For bromide-free de- 
veloper this is a good description of the actual experimental result. 

If, however, the developer contains free bromide, the various 
straight lines seem to originate from a common point below the 
exposure axis and "depressed" by a density D as shown in Fig. 
11(6). This relation is amply discussed in the Eastman Kodak 
Monograph No. 2 3 on the theory of photography, to which we shall 
refer for additional experimental facts. 

In order to explain this behavior one must give up the idealization 
that all halide grains are of uniform size and nature, and must take 
into account the fact that the actual halide grain areas are distributed 
around an average value in a probability function which, again, is 
subject to statistical analysis. Since photographic speed contains 
the probability of the photon's scoring two direct hits on the grain, 
it varies approximately with the square of the halide grain area. 
The contribution of the grain to the density varies with the area of 
the developed grain. Strictly spaeking, one ought to compute the 

440 W. J. ALBERSHEIM [J. S. M. p. E. 

H&D curve differential for each particular grain size and integrate 
over all grain sizes. Fortunately, this integration does not greatly 
affect the shape of the actual H&D characteristic because even 
with the simplified assumption of uniform grain size, equation 79 
is an integral of the density differentials in a great number of thin 
emulsion slices exposed to exponentially decreasing light intensities. 
The density differentials "mix easily." 
The analytical description of Fig. 1 1 (6) is 

D = r(log e - log - D (90) 

In order to keep log i and D constant regardless of development 
time, there must be a definite relation between the areas of silver 
grains being developed from halide grains of different sizes. This, 
then, forces us to investigate the equations for the velocity of de- 
velopment. The first step consists in finding the functional relation 
required by Fig. 11(6) and equation 90. 

Instead of considering the innumerable different halide grain 
sizes, let us limit the number of grain sizes to 2, because this will 
suffice for an analysis of the problem. Assume, therefore, that D 
is built up of two components of the type 88. Their sum must 
conform to equation 90; hence: 

D = iai(log e log ii) + 2 a 2 (log log i z ) = T(log e log i) ,D (91) 
Since this is true regardless of the value of e, 

r = kiai + k&z (92) 


&2 log t log i-i log i log t' 2 

Since 02 can never be negative, equation 90 can be satisfied only for 

ai > log * - log i 
and for 


log i, - log i 

For high values of T the constant subtraction term of 93 becomes 
relatively unimportant, and a z outgrows ai. Forgetting mathe- 
matics for the moment, let us form a mental image of the mechanism 
involved. Assume that each halide grain has one sensitizing con- 
centration speck on its surface. The larger grains have a greater 



chance to be hit by light, hence a smaller "inertia." For any given 
exposure, a fixed proportion of large and small grains is activated. 
As development of each grain begins it must proceed inward from 
the small concentration speck, and in the early stages of development 
all the silver grains grow at the same rate. Thus the low-r, H&D 
curve acts as if the weight of the large and small components were 
equal, and the inertia point is halfway between those of large and 
small grains. As development proceeds, the smaller halide grains 
become fully converted into metallic silver, and the larger halide 
grains begin to outstrip them in silver deposition. Thus the H&D 
curve, following the weighted average, shifts nearer and nearer the 
lower inertia point of the larger halide grains. 

There remains the question as to the chemical process that pro- 

5 to if 20 

FIG. 12. Development characteristic. 

duces grain-size ratios in accordance with equation 93. The answer 
may be deduced from inspecting development-velocity curves typical 
of bromide developers. In Fig. 12 the circles show observed values 
copied from Fig. 27(^4) of the Eastman Kodak monograph. 3 

The predominant shape approximates an exponential approach to a 
saturation value, like the voltage at the terminals of a condenser 
that is being charged by a constant voltage through a resistance. 
But there is a time delay, which A. H. Nietz calls induction period, 
and a tendency towards a square-law incr8ase (as if a small inductance 
were added to the resistance in our electrical analogy) which strongly 
suggest a 2-phase chemical process. 

As a working hypothesis assume that the relatively fast first phase 
consists in dissolving and breaking down the halide crystals so that 
silver ions are present in solution in the little hole or crack previously 
occupied by the halide grain. It is this first phase that begins at a 

442 W. J. ALBERSHEIM [J. S. M. p. E. 

rate independent of grain size. This dissolving process is slowed 
down by the presence of free bromide in the solvent. 

As soon as silver ions are in solution they are precipitated at a rate 
characteristic of the developer and deposited upon the walls of the 
grain hole and of adjoining cracks in the emulsion. Since this is 
akin to a "plating" process, it offers an explanation for the thin and 
flake-like structure of the silver grains (eq. 48V) which was previously 
deduced from the "photometric constant"; that is, the weight of 
silver per sq. cm. divided by the density. 

Putting all the above reasoning into the mathematical language 
of a mass-action differential equation, one finds : 

dt hb 
%-C(j-o) (97) 

in which b expresses the retarding effect of the bromide and c the rate 
of silver deposition, or generally the speed of the second phase. The 
solutions are: 


the initial rate of change of which displays the required independence 
from h, and 

-[' + r=^B --"" - r=TB '""] <"> 

If the dissolving or ionizing phase proceeds with much higher 
speed than the depositing phase, the second term of 98b will soon be 
negligibly small, so that 98b can be approximated by 

This can be interpreted in the form: 

a = 

in which the "induction period" is 

A* -- iln(l-CM)-*6 (101) 

In the example of Fig. 12, this period amounts to 1.4 minutes. 
The other way of writing equation 99 is 


If two sizes of halide grains were present in the emulsion, 

__*!__ M _ t -0t] - Ckl * 


*? n - *-ct] - 

from which 

*,(! - Chib) Clhbfo - hi) , inc . 

a-i = di j-j- . -=-=- AI Ci A. 2 (.105) 

This equation is independent of time ; it has exactly the form of 
equation 93, which corresponds to the common origin of all straight- 
line portions from one "depression point." 

By comparing 93 and 105 one finds 

1 - 

(log i log iz) depends upon properties of the undeveloped halide 
grains. If one maintains, for instance, the previously introduced 
assumption that the speed is proportional to the square of the halide 
grain area, then 

**<-**- ^ van 

in which ki and kz denote the relative abundance of grain areas hi 
and hz. One thus finds that for a given emulsion all terms but the 
first on the right side of equation 106 are constants. Therefore 


Do = Constant ^-^ (108) 

1 ^~ 

or, for small depressions, 

D = Constant Cb (109) 

Comparing this with equation 101, 

DO = Constant M (110) 

For a given emulsion, the bromide depression is approximately 
proportional to the induction time and, of course, to the free bromide 

If one considers various emulsions, one finds from equations 106 
and 107 that the bromide depression is proportional to (hi h^) 

444 W. J. ALBERSHEIM [J. S. M. P. E. 

and to log (h^/hi). Both these factors approach zero for the limit of 
uniform grain size; for small values, the depression is therefore 
proportional to the square of the mean relative variation of the 
silver halide grain size. 

The statistical method applied to the microscopic silver halide 
grains before, during, and after development has thus accounted for 
the large-scale phenomena of noise, contrast, speed, and develop- 
ment characteristics. It has predicted some previously unknown 
relations, which were verified by experiments, and others that still 
remain to be tested. 

Symbol Dimension 

A Area of scanning slit cm* 

a Area of silver grain cm 2 

d Diameter of silver grain cm 

N Maximum silver grain number in slit 

M Average silver grain number in slit 

M' Instantaneous silver grain number in slit 

T Average transmission 

T' Instantaneous transmission 

D t Average density, base e ( In T) 

D Average density, base 10 ( log T) 

D' Instantaneous density, base 10 (log T) 

SM Actual deviation of M 

ST Actual deviation of T 

SD Actual deviation of D 

AM Probable deviation of M 

AT Probable deviation of T 

&D Probable deviation of D 

P Probability 

V Volume of emulsion under slit cm 1 

v Volume of a silver grain cm 1 

W Average weight of silver under slit g 

w Weight of a silver grain g 

p Density of silver g cm~ 3 

Ag Weight of silver per cm 2 of sound track gcm~ 2 

Y Thickness of emulsion cm 

y. Thickness of grain cm 

L Power level db 

n Maximum silver grain number per unit area cm" 2 

m Average silver grain number per unit area cm ~ 2 

Q Average silver grain surface per unit area 

T Translucence of unexposed emulsion 


h Area of unexposed halide grain cm* 

y Extension in depth cm 

r Halide grains hit by at least one photon 

g Halide grains hit by at least 2 photons 

5 "speed" factor or "sensitivity" dyne" 1 

u Turbidity cm" 1 

E Exposure dynes 

e Relative exposure 

b Bromide content 

c Rate of silver deposition sec" 1 

7 Area of dissolved silver ions in grains cm 2 

Basis of natural logarithms 

In Natural logarithm, basis e 

log Common logarithm, basis 10 

* Inertia 


1 Ross, F. E.: "The Physics of the Developed Photographic Image," D. Van 
Notirand Co. (New York), 1924, p. 46. 

2 J. Opt. Soc. Amer. (Oct., 1936), p. 367. 

3 NIETZ, A. H.: "The Theory of Development," D. Van Nostrand Co. (New 
York), 1922, pp. 35, 77. 


During the Conventions of the Society, symposiums on new motion picture appara- 
tus are held, in which various manufacturers of equipment describe and demonstrate 
their new products and developments. Some of this equipment is described in the 
following pages; the remainder will be published in subsequent issues of the Journal. 



The technical problems faced by a motion picture processing laboratory are 
fundamentally the same regardless of the size of the plant or its location. Meth- 
ods that will produce first-quality results will do so whether they are applied 
to a few thousand feet of film or to millions of feet of film per week. 

The problem of applying these methods on a commercially profitable basis, 
however, varies directly with the volume of film being handled. Installing such 
modern methods as machine development of negative and positive film, accurate 
sensitometric control, and the like, may be more complicated and expensive in 
the case of a large plant; but once the installation of equipment and routine is 
made, the investment speedily justifies itself. 

In the smaller plant, that is not always the case. Unless the designing engi- 
neer of such equipment takes into consideration the economic, as well as the 
technical circumstances under which such a plant operates, the investment in 
money and plant space involved in the installation is likely to bear an unprofit- 
ably high ratio to the maximum potential savings attainable by using the modern 

At the same time, the technical advantages of better and more uniform process- 
ing, and the cash savings achieved through minimizing the footage spoiled by in- 
correct processing, can be even more important in the smaller plant than in the 
large one. 

The large laboratory can count upon practically continuous operation through- 
out the year; the smaller plant's operation is more generally intermittent. In 
the large plant there is generally a more or less variable volume of negative de- 
velopment and daily printing, counterbalanced by a fairly steady flow of release 
printing. Further, such a plant will usually handle the output of several producing 
units, or, as in the case of a commercial laboratory, that of several independent 
units or studios. 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif.; received May 
24, 1937. 

** Art Reeves Motion Picture Equipment Co., Hollywood, Calif. 



In the smaller plant, on the other hand, the laboratory's activity is more gener- 
ally keyed to the activity of one or two producing units with the possibility of 
occasional commercial work. When the unit is in production, the plant's output 
is chiefly negative development, with a minimum of daily print footage; when the 
production is finished there is a varying amount of release print making. In 
some cases this must be done on 16-mm. as well as on 35-mm. film. 

To install the type of machinery used in a major laboratory in a plant oper- 
ated under these conditions would be economically unsound. Suppose, for in- 
stance, that developing machines were installed upon the same basis common in 

FIG. 1. Complete developing machine installation (front view). 

the large Hollywood plants, where one machine or battery of machines is used ex- 
clusively for developing negative film, and a second machine or group of machines 
exclusively for positive. In the large plant, both machines will be kept busy al- 
most continually. In the average smaller plant outside such production centers 
as Hollywood, New York, and London, one machine or the other would be stand- 
ing idle, and therefore profitless, for long periods of time. 

It is, of course, possible in several excellent machines to vary the developing 
time sufficiently that the same machine can be used for developing either nega- 
tive or positive film. Such machines, however, almost always require more 
or less involved re-threading of the film webs, or draining and refilling the 
developer tanks for the change, so they can not truly be called all-purpose ma- 
chines in the commercial sense of the term. 



To meet this need, the developing machine described herein has been pro- 
duced during the past year. It is definitely an all-purpose machine, being adapt- 
able to developing negative or positive film without either re-threading the film- 
web or re-filling the tanks. It will handle either 35-mm. or 16-mm. film inter- 
changeably. It occupies the smallest amount of floor space possible without 
unduly restricting either capacity or efficiency. 

At the same time, the machine makes no compromise in the matter of quality. 
It is engineered according to the most approved and modern standards. The 
film is under a minimum of tension, driven by the rollers at the bottom of each 
loop; no sprockets are used. The developing solutions are circulated continu- 

, f t id** it**'****** 

tttti M til 

FIG. 2. Negative development tank. 

ously through a special manifold system that produces turbulation sufficient to 
avoid directional markings. The temperature of all solutions is thermostatically 
controlled, as is the temperature and humidity of the drying compartment. A 
special pneumatic squeegee eliminates carrying over the solutions. All mate- 
rials have been carefully chosen for their lack of chemical effect upon the solutions 

The tanks are of wooden construction. The framework for the machinery is 
largely duralumin. All metal-work in contact with either solutions or film is 
stainless steel, while generous use has been made of bakelite, celoron, and similar 
non-corrosive plastics for such parts as film-carrying rollers, immersed driving 
gears, circulating pumps, and the like. The solutions are circulated through 
special hard-rubber tubing and flexible rubber piping. 

Oct., 1937] 



The machine is shown in Fig. 1. In the standard installation, it occupies two 
small rooms. The tank section shown in the foreground occupies one room, 
which is safely darkened. The drying compartment, air-compressors, and motors 
occupy the other room, which may be illuminated by normal white light. The 
film passes from one room to the other in a metal tube passed through the wall. 

There are seven compartments in the composite tank unit : positive developer 

FIG. 3. Developing solution circulating systems. 

tank, negative developer tank, rinse tank, hypo tank, wash tank, and two small 
storage tanks for negative developer and positive developer, respectively. 

The two storage tanks are at the outer end of the tank unit. Over them is the 
light-tight feed magazine which carries the undeveloped film on a standard 2000- 
f t. reel and is protected by an automatic alarm that warns of the approach of the 
end of a reel. 

Next comes the positive developing tank. Next to it is the negative developing 
tank (Fig. 2). In both these sections of the machine, the film loop starts at the 
left-hand side of the machine and crosses the tank in a thin horizontal spiral, 
passing to the rinse tank from the right-hand end of the loop. 

Both loops are kept threaded at all times. If, as seen in Fig. 2, positive film 
is being developed, the leader in the negative tank is simply broken from the 


strand and allowed to hang loosely in the tank, with the ends clipped to the 
frame. As the film drive is from the bottom of the loop only, and in this in- 
stance the loop hangs clear of the bottom driving rollers, the film in this tank does 
not move. 

When the machine is to be used for developing negative, the positive-tank 
leader is similarly broken from the strand, and the ends of the negative loop re- 
connected to the main strand with film clips. 

Two separate systems are used to circulate the developing solutions (Fig. 3). 
The negative developer circulating system is entirely independent of that used 
to circulate the positive developer. Thus when the machine is in use only one of 
the developer-circulating systems need be kept in operation. 

In either case, the overflow from the developing tank feeds directly into the 
appropriate storage tank. From the storage tank the solution passes through a 
specially built centrifugal pump, constructed entirely of bakelite and celoron, 
through external tubing of rubber to the bottom of the developing tank. Here 
it is directed along one side of the narrow tank, from which it recoils with a whirl- 
ing motion that imparts the necessary turbulation to the solution. 

Each of the two circulating systems has its own independent temperature-control 
system. A stainless steel encased electric heating unit is placed at the bottom 
of each storage tank, and is connected in series to a three-positioned Mercoid 
switch. Connected also to this switch may be an electric refrigerating unit, through 
which the solution is pumped in stainless steel tubing. The thermostats auto- 
matically hold the solution within a range of 3 of any predetermined tempera- 
ture. The temperatures of the solutions in the developing tanks are indicated 
by two separate thermometers mounted on the side of the tank assembly. 

The film-moving mechanism is of the conventional type (Fig. 4). It is sup- 
ported by a rigid duralumin frame which may be hoisted clear of the tanks. 
All parts of this assembly that are immersed in the solutions are made of stain- 
less steel, bakelite, or celoron. 

The main driving shaft extends the full length of the tank unit, on the right- 
hand side. At each film loop a gear-driven vertical shaft extends to the bottom 
of the loop where, by means of bakelite bevel gears, it drives a stainless steel 
shaft upon which are fixed the driving rollers. The film is under tension only 
when the take-up brings it into contact with these powered rollers; otherwise it 
moves freely on the free-rolling upper rollers. 

As the film passes from each tank, it goes between a pair of bakelite nozzles 
from which downward-slanting currents of air are directed against the faces of the 
film. This results in a squeegeeing action that virtually eliminates carrying over 
solutions from one tank to the other. There is therefore no dilution, and the 
solutions have a considerably increased active life. 

In the farther room, as has been stated, are the drying compartment, two sepa- 
rate air-circulating systems, and the variable-speed film-moving drive. This 
drive while using a constant-speed electric motor, acts like an infinitely variable 
transmission and permits any variation in developing time between l s / 4 minutes 
and 18 minutes. The variation is controlled by a small controlling wheel placed 
immediately below an indicating tachometer. 

Two independent air-circulating systems are used: ' a high-pressure system for 
the pneumatic squeegees, etc., and a low-pressure system for the film-drying 

Oct., 1937] 



compartment. Both normally draw their air from the room in which the dry-box 
end of the machine is located. The high-pressure system, driven by its own elec- 
tric motor, uses a rotary compressor. An efficient air-cleaner is fitted to its 
intake, and special non-back-pressure silencers are fitted to both the intake and 
the exhaust lines, to minimize the noise of operation. A safety-valve is also fitted 
to the exhaust line. This high -pressure air system is of sufficient capacity to take 
care of the needs of two of these machines if necessary. 

The low-pressure system draws its air through a large manifold fitted with two 
large intake ports protected by interchangeable air-filters of spun glass impreg- 

FIG. 4. Complete installation, showing film-moving mechanism and drying 
cabinet (rear view). 

nated with viscous oil. After filtering, the air passes a heater unit which warms 
it to the desired temperature for drying the film. This heater has two degrees of 
heating the high setting drawing 10 kw. and the low 5 kw. Both are thermo- 
statically controlled. When the machine is to be used in localities where ab- 
normally high temperatures are to be encountered, an electric air-cooling unit 
may also be fitted. A separate thermostat operates a warning bell in case of any 
failure of either the air-circulating fan or the heater-units. 

The fan forces 1000 cubic feet of air per minute into the film-drying compart- 
ment. The air enters at the bottom of the compartment and is directed upward 
by four adjustable deflecting vanes. A second thermostat guards the tempera- 
ture of this drying compartment, holding it within a range of 3 of any predeter- 
mined figure. 


The drying compartment is constructed along conventional lines. It is of sheet 
metal, with two large glass-paned doors on either side. The film moves through 
this compartment much as it does through the solution tanks, being carried on 
bakelite rollers. Only the lower rollers are driven, while the upper rollers revolve 
freely on ball bearings. In the middle of each film loop in this compartment is a 
large cloth-covered drum which revolves freely and serves to polish the celluloid 
surface of the film. 

The usual vapor-proof lamps illuminate the inside of the drying cabinet and 
facilitate inspection of the film as it dries. 

Emerging from the drying compartment, the film is taken up on a standard 
2000-ft. reel, driven by an equalized belt drive. 

In every possible respect, a high factor of safety has been provided in the 
machine. The power units, heating units, compressors, solution pumps, and 
the like, are generously over-sized. The film-moving drive, for instance, actually 
requires only Vio hp. for normal operation, yet a 1 /4-hp. motor is used. In the 
same way, the undeveloped film is fed from a standard 2000-ft. reel, requiring 
that the film be rewound to reveal any breaks or tears that may have been occa- 
sioned in the camera. 

A similar equipment problem is encountered in the matter of applying the 
accuracy of sensitometric control to the routine of laboratory operations. The 
majority of standard sensitometers are built with such involved care for every de- 
tail that could possibly affect their accuracy that they are prohibitively expensive 
for the average laboratory. In the large film centers this is to some extent offset 
by the excellent service maintained by the raw-film manufacturers, who make 
sensitometric strips for the laboratories using their products. But elsewhere the 
average laboratory in which sensitometric control is more likely to be needed is 
too remotely located to take advantage of this service, and not financially able to 
purchase a standard sensitometer. 

To meet this need, the Artreeves Sensitester has been developed. This is a 
simple, accurate light-test machine that may be converted into a practical sensi- 
tometer by moving a single control. 

The Sensitester is shown in (Fig. 5). Essentially it consists of a supporting 
stand, a light-metering assembly, and mechanisms to carry and move the film 
being tested and that upon which the test is made. 

When used as a film light-tester, the negative to be tested is threaded from one 
rewind to the other, across the light-metering assembly. The positive film upon 
which the light-test is to be printed is threaded from the feed magazine, over a 
sprocket and under a pressure-pad or platen, past another sprocket and into the 
take-up magazine. For the sake of safety, these magazines are fully enclosed, 
to minimize the possibility of the film's being fogged through prolonged exposure 
to the "safe" light of the testing room. 

When making a test, the horizontal bar extending across the front of the ma- 
chine is depressed. This lowers the platen and magazine assembly, bringing the 
two films into contact across the exposure plane. At this moment, the expo- 
sure is made automatically. As the control bar is raised, the exposed section of 
positive film is automatically wound into the take-up magazine and replaced by a 
fresh section for the next test. 

The light is metered through a series of adjustable diagragms that may be 

Oct., 1937] 



pre-set to coordinate with the characteristics of the printer used, giving eleven 
graduated exposure-steps corresponding to printer-lights 1 to 21. In addition to 
printing these light-test frames from the picture area of the negative, the machine 
also prints the marginal footage-numbers, eliminating any change of confusion in 
regard to similar "takes." 

Timing the exposure is accurately controlled by an adaptation of the metronome 
principle. A counterweighted pendulum arm is used, the position of one of the 

FIG. 5. The Sensitester. 

weights being adjustable. This controls the time of the pendulum's swing. As 
the platen is brought down to make the exposure, the metronome arm is auto- 
matically released : as it starts its travel, it switches on the exposing light ; as it 
finishes its return stroke, it switches off the light, and is itself locked into place 
ready for the next test. 

Combining these two principles of proved accuracy for this purpose makes it 
possible to utilize the same machine as a practicable sensitometer. Since the 
metronome principle gauges the exposure, no outside factor can alter this timing. 
Since the light for all steps comes from a single source at one exposure and is 
metered through a fixed series of diaphragms, the relative exposures of the various 
steps can not be disturbed. 


Therefore a supplementary series of fixed diaphragms is built into the machine. 
Each of these diaphragms admits light in a fixed, logarithmically progressing 
ratio. When making sensitometric strips on negative film, a supplementary 
filter may be fitted to match the light to daylight standards. 

The resulting sensitometric strip contains only half as many gradations as 
those made on a standard sensitometer ; but the strips have been made to match 
identically the alternate steps of standard sensitometric strips. For the practical 
purposes of the average laboratory, these strips have been found to serve quite 
as well as the standard type. It is obvious that since the gamma is a function 
primarily of the straight-line portion of the H&D curve, which may be plotted 
equally well from less closely spaced points, the gamma may be determined from 
these simpler strips with equal accuracy. 

This design has been engineered so that it will maintain its fundamental ac- 
curacy regardless of external conditions. Variations in current supply, for ex- 
ample, while affecting the overall result, can not upset the relation between the 
individual exposure-steps, since all are made at a single exposure, from a common 
light-source, with the gradations produced by metering the light optically. Such 
fluctuations can not affect the timing, since this is not done by motors, but by the 
uniformity of metronome control. 

From the viewpoint of practical laboratory operation, this machine is doubly 
advantageous. In addition to the lowered equipment cost obviously gained by 
combining two instruments into one, there is the further advantage of making it 
possible to utilize more frequently the advantages of sensitometric control as a 
routine check on the accuracy of laboratory operations. Separate machines 
might not be used so frequently in routine operations, but with the two instru- 
ments in one unit, accurate sensitometric strips can be made as easily and as fre- 
quently as ordinary light-tests. 



The editors present for convenient reference a list of articles dealing with subjects 
cognate to motion picture engineering published in a number of selected journals. 
Photostatic copies may be obtained from the Library of Congress, Washington, D.C., 
or from the New York Public Library, New York, N. Y. Micro copies of articles 
in those magazines that are available may be obtained from the Library of the U. S. 
Department of Agriculture, Washington, D. C. 

American Cinematographer 

18 (Aug., 1937), No. 8 

New Film Editing Aid Gives Larger Picture (p. 318). 
How One Cinematographer Secures Variable Diffusion 
(p. 328). T. SPARKUHL 


13 (July 6, 1937), No. 11 

Bedingungen fur gute Bild-und Tonwiedergabe (Re- 
quirements for Good Projection and Good Sound 
Reproduction) (p. 118). E. KAMMERER 

Entwicklung der Hochfrequenzkinematografie (Evolu- 
tion of High-Speed Motion Pictures) (p. 121). F. E. v. ECKARD 

Lichtpolarisatoren beim Raum- und Mehrfarbenbild- 
wurf (Use of Polarizers for Stereoscopic and Color 
Projection) (p. 123). O. BENDER 

International Projectionist 

12 (July, 1937), No. 7 
The Neon Tube Oscilloscope as a Precision Servicing 

Instrument (p. 18). T. P. HOVER 

Typical Troubles in Modern Sound Reproducing Units 


Motion Picture Herald (Better Theatres Section) 

128 (July 24, 1937), No. 4 
Theater Acoustics Today (p. 39). C. C. POTWIN 

Photographische Industrie 

35 (July 21, 1937), No. 29 

Neues iiber ein Kino-Aufnahmeobjektiv mit verander- 
licher Brennweite (Announcement about a Motion 
Picture Lens Having a Changeable Focal Length) 
(p. 793). 



Radio Engineering 

17 (July, 1937), No. 7 
Plate Efficiency of Class "B" Amplifiers (p. 14). P. ADORJAN 

RCA Review 

11 (July, 1937), No. 1 
Television Studio Design (p. 14). R. M. MORRIS AND 

Television Transmitter Operating at High Powers and 

Ultra-High Frequencies (p. 30). J. W. CONKLIN AND 


"Batalum," a Batium Getter for Metal Tubes (p. 117). E. A. LEDERER AND 


La technique cinematographique 

9 (June, 1937), No. 78 
L'Emulsion Cinematographique et Son Emploi (Motion 

Picture Emulsion and Its Applications) (p. 950). A. P. RICHARD 

Une Belle Projection en Couleurs en 16-Mm. (Good 

16-Mm. Color Projection) (p. 955). G. VIEL 


10 (Aug., 1937), No. 114 

Television Projection with the Cathode-Ray Tube 
(p. 457). 




Officers and Committees in Charge 

W. C. KUNZMANN, Convention Vice-President 

J. I. CRABTREE, Editorial Vice-President 

S. K. WOLF, President 

G. FRIEDL, Jr., Chairman, Atlantic Coast Section 


G. E. MATTHEWS, Chairman 







Local Arrangements and Reception Committee 

G. FRIEDL, JR., Chairman 






Registration and Information 

W. C. KUNZMANN, Chairman 

Ladies' Reception Committee 

MRS. S. K. WOLF and MRS. O. F. NEU, Hostesses 





Banquet Committee 

A. S. DICKINSON, Chairman 






Publicity Committee 

W. WHITMORE, Chairman 



Projection Committee 

H. GRIFFIN, Chairman 





Officers and Members of New York Projectionists Local 306. I. A. T. S. E. 

Membership Committee 

E. R. GEIB, Chairman 




The headquarters of the Convention will be the Pennsylvania Hotel, where ex- 
cellent accommodations have been assured and a reception suite will be provided 
for the Ladies' Committee. An excellent program of entertainment will be ar- 
ranged by the hostesses. 

Special hotel rates guaranteed to SMPE delegates, European plan, will be 
as follows: 

One person, room and bath $3 . 50 

Two persons, double bed and bath 5 . 00 

Two persons, twin beds and bath 6 . 00 

Parlor suite, one person 11 .00 up 

Parlor suite, two persons 13. 00 up 

Everyone who plans to attend the Convention should return his reservation card 
to the Hotel promptly in order to be assured of satisfactory accommodations. 
Consult your local railroad ticket agent with regard to coach and pullman rates. 

Parking accommodations will be available to those who motor to the Conven- 
tion at the fire-proof garage of the Hotel, at the rate of $1.25 for twenty-four hours 
or $1.00 for twelve hours, including pick-up and delivery at the door of the Hotel; 
weekly rate, $7.50. 


Registration headquarters will be located on the eighteenth floor of the Hotel at 
the entrance of the Salle Moderne, where the technical sessions will be held. Ex- 
press elevators from the lobby will be reserved for the Convention. All members 
and guests attending the Convention are expected to register and receive their 
badges and identification cards required for admission to certain evening sessions 
of the Convention, as well as to the Radio City Music Hall, Paramount Theater, 
Warner Bros. Strand Theater, and the Roxy Theater, which will hpnor the cards 
as courtesy admissions. 

Oct., 1937] FALL CONVENTION 459 

Luncheon and Banquet 

The usual informal get-together luncheon will be held at noon on October llth 
in the Roof Garden of the Hotel, and the semi-annual banquet and dance will 
take place on the evening of October 13th. 

Addresses will be delivered by prominent members of the industry on both 
occasions. At the banquet the annual presentation of the SMPE Progress Medal 
and the Journal Award will be made, and the officers-elect for 1938 will be intro- 
duced. The banquet will conclude with dancing and entertainment. 

Tickets for admission to the informal luncheon and the banquet may be ob- 
tained at the registration desk. Banquet tables reserved for 8, 10, and 12 per- 

Points of Interest 

Headquarters and important branch offices of practically all the important firms 
engaged in producing, processing, and exhibiting motion pictures and in manu- 
facturing equipment therefor, are located in metropolitan New York. Although 
no special trips or tours have been arranged to any of these plants, the Conven- 
tion provides opportunity for delegates to visit those establishments to which they 
have entree. Among the points of interest to the general sightseer in New York 
may be listed the following: 

Metropolitan Museum of Art. Fifth Ave. at 82nd St.; open 10 A.M. to 5 P.M. 
One of the finest museums in the world, embracing practically all the arts. 

American Museum of Natural History. 72nd St. between Columbus Ave. and 
Central Park West ; 9 A.M. to 5 P.M. 

New York Museum of Science and Industry. RCA Building, Rockefeller Cen- 
ter; 10 A.M. to 5 P.M. Exhibits illustrate the development of basic industries, 
arranged in divisions under the headings food, industries, clothing, transportation, 
communications, etc. 

Museum of the American Indian. -Broadway and 155th St., 2 P.M. to 5 P.M. 

Hayden Planelarium. Central Park West at 77th St. Performances at 11 A.M., 
2 P.M., 3 P.M., 4 P.M., 8 P.M., and 9 P.M. Each presentation lasts about 
45 minutes and is accompanied by a lecture on astronomy. 

Rockefeller Center. 49th to 51st Sts., between 5th and 6th Aves. A group of 
buildings including Radio City Music Hall, the Center Theater, the RCA Building, 
and the headquarters of the National Broadcasting Company, in addition to 
other interesting general and architectural features. 

Empire State Building. The tallest building in the world, 102 stories or 1250 
feet high. Fifth Ave. at 34th St. A visit to the tower at the top of the building 
affords a magnificient view of the entire metropolitan area. 

Central Park. 59th to 110th Sts., Central Park West to Fifth Ave. Here are 
located the Metropolitan Museum of Art, and a number of other general and 
educational features including the zoological garden and "Cleopatra's Needle." 
The latter is an Egyptian obelisk presented to the City in 1879 by the Khedive of 

Greenwich Village. New York's Bohemia; a study in contrasts. Here are 
located artists and artisans, some of the finest homes and apartments, and some 
of the poorest tenements. 

Holland Tunnel. The first vehicular tunnel constructed beneath the Hudson 


River; at Canal St., connecting New York with New Jersey; more than 9000 
feet long. 

Foreign Districts. Certain sections of the city are inhabited by large groups of 
foreign-born peoples. There is the Spanish section, north of Central Park; the 
Italian district near Greenwich Village; Harlem, practically a city in itself, num- 
bering 300,000 negroes; Chinatown, in downtown Manhattan; the Ghetto, the 
Jewish district; and several other such sections. 

Miscellaneous. Many other points of interest might be cited, but space permits 
only mentioning their names. Directions for visiting these places may be obtained 
at the Convention registration desk: Pennsylvania Station, Madison Square, 
Union Square, City Hall, Aquarium and Bowling Green, Battery Park, Washing- 
ton Square, Riverside Drive, Park Avenue, Fifth Avenue shopping district, Grand 
Central Station, Bronx Zoo, St. Patrick's Cathedral, St. Paul's Chapel, Cathedral 
of St. John the Divine, Trinity Church, Little Church Around the Corner, Wall 
St. and the financial district, Museum of Natural History, Columbia University, 
New York University, George Washington Bridge, Brooklyn Bridge, Triborough 
Bridge, and Statue of Liberty. 

Steamships. The S. S. Normandie will be in dock open for inspection, on Octo- 
ber 12th, pier 88 at the foot of West 48th St. ; tickets on sale at the pier, 50|< each. 


9:00 a. m. Salle Moderne; Registration. 

10:00 a. m. 
to 12:00 p. m. Salle Moderne; Business and General Session. 

Opening Remarks by President S. K. Wolf (10 Min.) 

Report of the Convention Committee; W. C. Kunzmann, 
Convention Vice-President (5 Min.) 

Report of the Membership Committee; E. R. Geib, Chairman 
(5 Min.) 

Society Business; Election of Officers and Other Business 
(20 Min.) 

"Hunting with a Microphone the Songs of Vanishing Birds;" 
P. Kellogg, Laboratory of Ornithology, Cornell University, 
Ithaca, N. Y. (Demonstration.) (30 Min.) 

"Safeguarding and Developing Our Film Markets Abroad;" 
N. D. Golden, Motion Picture Division, U. S. Department 
of Commerce, Washington, D. C. (20 Min.) 

"High-Speed Motion Picture Photography Applied to the 
Design of Telephone Apparatus;" W. Herriott, Bell Tele- 
phone Laboratories, Inc., New York, N. Y. (Demonstra- 
tion.) (20 Min.) 
12:30 p. m. Roof Garden; Informal Luncheon. 

For members, their families, and friends. 

Address by Mr. Louis Nizer, Secretary, New York Film Board 
of Trade, New York, N. Y. 

Address by Mr. Martin Quigley, President, Quigley Publishing 
Co., Inc., New York, N. Y. : "Propaganda, Education, and 
the Entertainment Film." 
2:00 p. m. 
to 5:00 p. m. Salle Moderne; Photographic and Laboratory Session. 

"Further Progress in Film Storage;" Capt. J. G. Bradley, 
National Archives, Washington, D. C. (20 Min.) 

"The Effect of the Composition of an MQ Developer on Its 
Reduction Potential;" R. M. Evans and W. T. Hanson, Jr., 
Kodak Research Laboratories, Rochester, N. Y. (20 Min.) 

"A Modern Motion Picture Laboratory;" C. L. Loot ens, Re- 
public Productions, Inc., North Hollywood, Calif. (20 

"Grain-Size Determination and Other Applications of the 
Callier Effect;" J. Eggert and A. Kiister, I. G. Farbenindus- 
trie Film Fabrik, Wolfen, Germany. (15 Min.) 



"Demonstration of Three-Dimensional Motion Pictures;" 
G. W. Wheelwright, 3d, Land-Wheelwright Laboratories, 
Boston, Mass. (1 Hour) 
8:00 p. m. 

to 10:30 p. m. Auditorium, Bell Telephone Laboratories; Special Sound Ses- 

"Distortion in the Reproduction of Hill-and-Dale Records;" 
M. J. Di Toro, Thomas A. Edison, Inc., Orange, N. J. (20 

"Recent Developments in Hill-and-Dale Recorders;" L. Vieth 
and C. F. Wiebusch, Bell Telephone Laboratories, Inc., 
York, N. Y. (Demonstration.) (20 Min.) 

"Nomenclature and Specifications Including Description of the 
Various Types of Movietone Release;" J. K. Hilliard, Metro- 
Goldwyn-Mayer Studios, Culver City, Calif. (Demonstra- 
tion.) (25 Min.) 

"Film Perforation and 96-Cycle Frequency Modulation in 
Sound-Film Records;" J. Crabtree and W. Herriott, Bell 
Telephone Laboratories, Inc., New York, N. Y. (15 Min.) 

"Push-Pull Recording;" J. G. Frayne and H. C. Silent, Elec- 
trical Research Products, Inc., Hollywood, Calif. (25 Min.) 

"Stereophonic Recording and Reproduction from Motion Pic- 
ture Film Records;" Introductory remarks by J. P. Max- 
field, Electrical Research Products, Inc., New York, N. Y. 
(Demonstration.) (15 Min.) 


10:00 a. m. 
to 12:30 p. m. Salle Moderne; Engineering Practice Session. 

"Air-Conditioning with Lithium Chloride;" G. A. Kelley, 
Surface Combustion Corp., Toledo, Ohio. (20 Min.) 

"The Activated Alumina System as Applied to Air-Condition- 
ing and Drying Problems;" G. L. Simpson, Pittsburgh 
Lectrodryer Corp., Pittsburgh, Pa. (20 Min.) 

"Die Castings and Their Application to Photographic Appli- 
ances;" C. Pack, Doehler Die Casting Co., New York, N. Y. 
(20 Min.) 

"The Use of Inconel for Photographic Film Processing Equip- 
ment;" G. L. Cox, International Nickel Co., Inc., New York, 
N. Y. (20 Min.) 

"Newer Types of Stainless Steel and Their Applications to 
Photographic Processing Equipment;" H. A. Smith, Re- 
public Steel Corp., Massilon, Ohio. (15 Min.) 

"Vacuum-Tube Engineering for Motion Pictures;" L. C. Hol- 
lands and A. M. Glover, RCA Manufacturing Co., Inc., 
Harrison, N. J. (25 Min.) 
2 :00 p. m. 
to 5:00 p. m. Salle Moderne; Lighting and Studio Session. 

Oct., 1937] FALL CONVENTION 463 

"Spectral Distribution and Color-Temperature of the Radiant 
Energy from Carbon Arcs Used in the Motion Picture Indus- 
try;" F. T. Bowditch and A. C. Downes, National Carbon 
Co., Inc., Cleveland, Ohio. (20 Min.) 

"Recent Developments in Background Projection;" G. G. 
Popovici, J. G. Saltzman, Inc., New York, N. Y. (20 Min.) 

"Recent Developments in Gaseous Discharge Lamps;" 
S. Dushman, Research Laboratory, General Electric Co., 
Schenectady, N. Y. (20 Min.) 

Report of the Studio Lighting Committee, R. E. Farnham, 
Chairman. (20 Min.) 

"Light Control in Photography;" G. Mili, Westinghouse Elec- 
tric & Manufacturing Co., Bloomfield, N. J. (20 Min.) 

"Modulated High-Frequency Recording as a Means of Deter- 
mining Conditions for Optimal Processing;" J. O. Baker 
and D. H. Robinson, RCA Manufacturing Co., Inc., Cam- 
den, N. J. (20 Min.) 

"Recording Tests on Some Recent High-Resolution Experi- 
mental Emulsions;" J. O. Baker, RCA Manufacturing Co., 
Inc., Camden, N. J. (20 Min.) 
8:00 p. m. 
to 11:30 p. m. Salle Moderne. 

Showing of selected historical motion pictures arranged by 
John E. Abbott, Director of the Film Library, The Museum 
of Modern Art, New York, N. Y. 

Showing of a recent feature picture and shorts. 


10:00 a. m. 

to 12:30 p. m. Salle Moderne; Projection Practice Session, A. N. Goldsmith, 

"The Practice of Projection;" A. N. Goldsmith, New York, 
N. Y. (5 Min,) 

"Grading Projectionists;" G. P. Barber, Government of the 
Province of Alberta, Edmonton, Alberta, Canada. (20 

"Cooperation as the Keynote of Successful Small-Town Projec- 
tion;" T. P. Hover, Warner's Ohio Theater, Lima, Ohio. 
(15 Min.) 

"A Discussion of Screen Image Dimensions;" F. H. Richard- 
son, Quigley Publishing Co., Inc., New York, N. Y. (15 

"New Approaches to the Presentation of the Motion Picture 
Theater;" B. Schlanger, New York, N. Y. (15 Min.) 

"Precision All-Metal Reflectors for Use with Projection Arcs;" 
C. E. Shultz, Heyer-Shultz, Inc. Montclair, N. J. (Demon- 
stration) ,(15 Min.) 


"Perforated Screens and Their Faults;" F. H. Richardson, 
Quigley Publishing Co., Inc., New York, N. Y. (10 Min.) 

"Commercial 16-Mm. Projection Faults;" C. L. Greene, Min- 
neapolis, Minn. (15 Min.) 

2:00 p. m. Open Afternoon 

7:30 p. m. Salle Moderne; Semi- Annual Banquet. 

Short addresses by eminent members of the industry; names to 

be announced later. 
Presentation of annual SMPE Progress Medal and Journal 

Entertainment and Dancing. 


10:00 a. m. 

to 12:00 p. m. Salle Moderne; Apparatus Symposium and Manufacturers' 

"The Sound-Level Meter in the Motion Picture Industry;" 
H. H. Scott, General Radio Co., Cambridge, Mass. (15 

"A New Motion Picture Camera Crane;" E. H. Heyer and 
E. L. Fischer, Universal Pictures Corp., Universal City, Calif. 
(15 Min.) 

"Non-Intermittent Projection;" J. F. Leventhal, Leventhal 
Patents, Inc., New York, N. Y. (15 Min.) 

"New Ideas in Mobile Sound Recording Equipment;" C. M. 
Ralph and J. G. Matthews, General Service Studios, Holly- 
wood, Calif. (15 Min.) 

"A Mobile Sound Recording Channel;" L. T. Goldsmith, 
Warner Brothers Pictures, Inc., Burbank, Calif. (15 Min.) 

"A Device for Cleaning the Sound- Track of Motion Picture 
Film during Projection;" R. V. Fisher, Flower City Speci- 
alty Co., Rochester, N. Y. (Demonstration.) (15 Min.) 

"A Recorder for Making Buzz-Tracks;" E. W. Kellogg, RCA 
Manufacturing Co., Inc., Camden, N. J. (10 Min.) 

"Advantages of Spark Illumination in Certain Types of Photog- 
raphy;" M. A. Durand, International Filmbook Corp., 
South Norwalk, Conn. (20 Min.) 

"A Flash Fire Valve for Fire Prevention in Motion Picture 
Projectors;" R. V. Fisher, Rochester, N. Y. (20 Min.) 

2:00 p. m. 
to 5:00 p. m. Salle Moderne; Sound Session. 

"Reduction of Loop-Length Variations in Non-Slip Printers;" 
E. W. Kellogg, RCA Manufacturing Co., Inc., Camden, 
N. J. (20 Min.) 
"Transmission Characteristics of Western Electric Re-Recording 

Oct., 1937] FALL CONVENTION 465 

Channels;" C. R. Daily and F. L. Hopper, Electrical Re- 
search Products, Inc., Hollywood, Calif. (20 Min.) 

"Permanent Magnet 4-Ribbon Valve for Portable Channel 
Push-Pull Recording;" E. C. Manderfeld, Electrical Re- 
search Products, Inc., Hollywood, Calif. (20 Min.) 

"Improvements in Noise-Reduction Circuits;" R. R. Scoville, 
Electrical Research Products, Inc., Hollywood, Calif. (20 

"Improved Methods of Detecting Light-Valve Overload;" 
C. R. Daily, Electrical Research Products, Inc., Hollywood, 
Calif. (20 Min.) 

"Overload Limiter for the Protection of Modulating Devices;" 
R. R. Scoville, Electrical Research Products, Inc., Holly- 
wood, Calif. (20 Min.) 

W. C. KUNZMANN, Convention Vice-President 

J. I. CRABTREE, Editorial Vice- President 

G. E. MATTHEWS, Chairman, Papers Committee 

This is a tentative program and, as such, is subject to change. The Society is not 
responsible for statements made by authors. 



Full details concerning the Fall Convention to be held at the Hotel Pennsyl- 
vania, New York, N. Y., October llth to 14th, together with the preliminary 
papers program, are contained hi the preceding section of this JOURNAL. 

A meeting of the Board of Governors will be held on October 10th at the 
Hotel Pennsylvania, at which time, in addition to usual administrative and 
financial matters, the final details of the Convention will be completed. 


At the first meeting of the season, held at the Hotel Pennsylvania, New York, 
N. Y., on September 15th, Mr. J. L. Forrest, of the Agfa Ansco Corp., Bingham- 
ton, N. Y., presented a paper describing the new Agfacolor process. 

The meeting was very well attended and considerable discussion followed the 
presentation, which was accompanied by examples of the Agfacolor process in 
slide-film form. 


At a recent meeting of the Admissions Committee at the General Office of the 
Society, the following applicants for membership were admitted to the Associate 


630 Fifth St., 52 Barcellow St., 

Huntington, W. Va. Port Jervis, N. Y. 


528 New Lots Ave., 109 R. Chignancourt, 

Brooklyn, N. Y. Paris, 18e, France. 


58-35 69th Lane, 45 Ohokayama, Meguro-ku, 

Maspeth, N. Y. Tokyo, Japan. 


38 Ambush St., 5 W. 63d St., 

Malvern, Johannesburg, New York, N. Y. 

South Africa. LINDSAY, W. W., JR. 

FRIEDLAND, B. 1539 Ensley Ave., 

2254 Davidson Ave., Hollywood, Calif. 

Bronx, N. Y. LOH, M. 

HARDWICK, T. D. 43 Passage 306 

757 Twelfth St., Rue La Tour, 

Wilmette, 111. Shanghai, China. 



550 Audubon Ave., 511 Pike St., 

New York, N. Y. Shinnston, W. Va. 


420 W. Evergreen Ave., 154 l /2 N. Arnaz Drive, 

Chicago, 111. Beverly Hills, Calif. 


6706 Drexel Ave., 522 Fifth Ave., 

Los Angeles, Calif. New York, N. Y. 


9 Haramachi, Shibuyaku, P. O. Box 1745, Caracas, D. F. 

Tokyo, Japan. Venezuela. 


30 State St., Sur 5-Num 109 

Cambridge, Mass. Caracas, Venezuela. 


Bombay Talkies, Ltd., 
Bombay-Malad, India. 


The following are available from the General Office of the Society, at the prices 
noted. Orders should be accompanied by remittances. 

Aims and Accomplishments. An index of the Transactions from October, 
1916, to December, 1929, containing summaries of all articles, and author and 
classified indexes. One dollar each. 

Journal Index. An index of the JOURNAL from January, 1930, to December, 
1935, containing author and classified indexes. One dollar each. 

SMPE Standards. Reprints of SMPE Standards and Recommended Practice. 
Twenty-five cents each. 

Membership Certificates. Engrossed, for framing, containing member's name, 
grade of membership, and date of admission. One dollar each. 

Lapel Buttons. The insignia of the Society, gold filled, with safety screw back. 
One dollar each. 

Journal Binders. Black fabrikoid binders, lettered in gold, holding a year's 
issue of the JOURNAL. Two dollars each. Member's name and the volume 
number lettered in gold upon the backbone at an additional charge of fifty cents 

Test- Films. See advertisement in this issue of the JOURNAL. 

S. M. P. E. 


These films have been prepared under the supervision of the Projection 
Practice Committee of the Society of Motion Picture Engineers, and are 
designed to be used as precision instruments in theaters, review rooms, 
exchanges, laboratories, factories, and the like for testing the perform- 
ance of projectors. 

Only complete reels, as described below, are available (no short sections 
or single frequencies). The prices given include shipping charges to all 
points within the United States; shipping charges to other countries are 

35-Mm. Sound-Film 

Approximately 500 feet long, consisting of recordings of several speak- 
ing voices, piano, and orchestra; buzz-track; fixed frequencies for focus- 
ing sound optical system; fixed frequencies at constant level, for de- 
termining reproducer characteristics, frequency range, flutter, sound- 
track adjustment, 60- or 96-cycle modulation, etc. 

The recorded frequency range of the voice and music extends to 10,000 
cps. ; the constant-amplitude frequencies are in 15 steps from 50 cps. to 
10,000 cps. 

Price $37.50 each, including instructions. 

35-Mm. Visual Film 

Approximately 500 feet long, consisting of special targets with the aid 
of which travel-ghost, marginal and radial lens aberrations, definition, 
picture jump, and film weave may be detected and corrected. 

Price $37.50 each, including instructions. 

16-Mm. Sound-Film 

Approximately 400 feet long; contents identical to those of the 35- mm. 
sound-film, with the exception that the recorded frequency range ex- 
tends to 6000 cps., and the constant-amplitude frequencies are in 11 
steps from 50 cps. to 6000 cps. 

Price $25.00 each, including instructions. 

16-Mm. Visual Film 

An optical reduction of the 35-mm. visual test-film, identical as to 
contents and approximately 400 feet long. 
Price $25.00 each, including instructions. 







Volume XXIX NOVEMBER, 1937 Number 5 



Some Lighting Problems in Color Cinematography 

T. T. BAKER 471 

Effect of Uneven Slit Illumination upon Distortion in Several 

Types of Variable-Width Records 


The Organisation and Activities of the Research Council of the 

Academy of Motion Picture Arts and Sciences 


A Linear Decibel-Scale Volume Indicator F. G. Albin 489 

Distortion in the Reproduction of Hill-and-Dale Recording. . . . 
M. J. Di TORO 493 

The Objective Quantitative Determination of the Graininess of 
Photographic Emulsions A. GOETZ AND W. O. GOULD 510 

New Motion Picture Apparatus 
A Sound Kodascope E. C. Fritts and O. Sandvik 539 

Current Literature 548 

Fall, 1937, Convention at New York, N. Y., October, llth 
to 14th 

Highlights of the Convention 550 

Final Program 555 

Abstracts of Papers and Presentations 559 

Society Announcements 573 





Board of Editors 
J. I. CRABTREE, Chairman 



Subscription to non-members, $8.00 per annum ; to members, $5.00 per annum, 
included in their annual membership dues; single copies, $1.00. A discount 
on subscriptions or single copies of 15 per cent is allowed to accredited agencies. 
Order from the Society of Motion Picture Engineers, Inc., 20th and Northampton 
Sts., Easton, Pa., or Hotel Pennsylvania, New York, N. Y. 
Published monthly at Easton, Pa., by the Society of Motion Picture Engineers. 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General and Editorial Office, Hotel Pennsylvania, New York, N. Y. 

West-Coast Office, Suite 226, Equitable Bldg., Hollywood, Calif. 
Entered as second class matter January 15, 1930, at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. Copyrighted, 1937, by the Society of 
Motion Picture Engineers, Inc. 

Papers appearing in this Journal may be reprinted, abstracted, or abridged 
provided credit is given to the Journal of the Society of Motion Picture Engineers 
and to the author, or authors, of the papers in question. Exact reference as to 
the volume, number, and page of the Journal must be given. The Society is 
not responsible for statements made by authors. 


President: S. K. WOLF, 100 E. 42nd St., New York, N. Y. 
Past-President: H. G. TASKER, Universal City, Calif. 

Executive Vice-President, G. F. RACKETT, 823 N. Seward St., Hollywood, Calif. 
Engineering Vice-President: L. A. JONES, Kodak Park, Rochester, N. Y. 
Editorial Vice-President: J. I. CRABTREE, Kodak Park, Rochester, N. Y. 
Financial Vice-President: O. M. GLUNT, 180 Varick St., New York, N. Y. 
Convention Vice-President: W. C. KUNZMANN, Box 6087, Cleveland, Ohio. 
Secretary: J. FRANK, JR., 90 Gold St., New York, N. Y. 
Treasurer: L. W. DAVEE, 250 W. 57th St., New York, N. Y. 


M. C. BATSEL, Front and Market Sts., Camden, N. J. 

A. S. DICKINSON, 28 W. 44th St., New York, N. Y. 

G. FRIEDL, JR., 25 Hunter Ave., Fanwood, N. J. 

A. N. GOLDSMITH, 444 Madison Ave., New York, N. Y. 

H. GRIFFIN, 90 Gold St., New York, N. Y. 

A. C. HARDY, Massachusetts Institute of Technology, Cambridge, Mass. 

K. F. MORGAN, 7046 Hollywood Blvd., Los Angeles, Calif. 

C. H. STONE. 205 W. Wacker Drive, Chicago, 111. 


T. T. BAKER** 

Summary. In additive processes the primaries are generally blue-violet, green, 
orange spectral bands, -which are not narrow and overlap to some extent. The ex- 
posure latitude of a color-screen process is less then that of black-and-white negative 
stock. Underexposures often tend toward excessive blue, and overexposures toward 
some other predominant color, due in some measure to differences in the foot and 
shoulder of the characteristic curves of the emulsion when exposed to the three primary 

Overexposure results in dilution of the colors, due to invasion of each primary into 
its neighbor's territory. There is thus a color-saturation latitude in the screen or 
matrix, distinct from a true emulsion latitude. The object here is to discuss a method 
of calculating the approximate range of studio light-intensity that will preserve the 
best color balance of which any particular additive process may be capable. 

For Dufaycolor film, a wedge spectrogram of suitable steepness is made representing 
average exposure, such as from a density of to 2.5. Upon development and reversal, 
the peaks throughout the wedge spectrum are shown as completely saturated (i. e., 100 
per cent of the reseau or matrix saturation). But as any spectral zone is followed 
downward from the peak, the color becomes diluted and may become even white as the 
image approaches the base line, and, therefore, maximum exposure. 

This is caused by the fact that, upon overexposure, scattering carries the light behind 
(say) a green element into the region of neighboring blue and red elements, so that the 
resulting color is reseau-green plus some blue and red, or reseau-green plus white. 
The effect is accentuated in reseau composed of less saturated color elements. By 
measuring from the peak to the position on any ordinate where distinct dilution be- 
comes apparent, the permissible range of light-intensity on the set can be computed 
from the difference of the log opacities of the two points on the ordinate. 

This paper relates to problems connected with the lighting range of 
the studios where additive systems of photography are employed. 
Additive systems depend upon the use of three primary elements. In 
the case of screen processes, these elements are of microscopic area in 
motion picture film stock. In the case of the lenticular process, three 
primary filters only are used of considerable area, in the camera and 
projector. In all cases, however, it is generally agreed that the filters 

*Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received May 
19, 1937. 

** Dufaycolor Research Laboratories, New York, N. Y. 


472 T. T. BAKER [J. S. M. P. E. 

employed transmit three spectral bands that overlap considerably, 
somewhat on the lines of the three visual sensation curves as deter- 
mined by Abney, Vierordt, Koenig, and others. The shape of the 
transmission curves of the niters involves a peak usually in the neigh- 
borhood of the dominant hue and tapers off in such a way as to over- 
lap its neighbors to a more or less extent. Taking the green filter, for 
example, minimum exposure would give an image using the peak of 
the transmission curve, while for an overexposure the transmission 
would encroach upon the adjacent areas of the blue and the red niters, 
the extent of encroachment increasing with increasing overexposure. 
The effect of overexposure is therefore tantamount to dilution of the 
primary color, since green, for example, upon overexposure will be- 
come green plus some blue and some red, making a total of green plus 
some white; in other words, a diluted green. 

There appear to be two kinds of latitude that require consideration 
in the use of an additive color process. One is the latitude derived 
from the characteristic curve of the emulsion ; the other is a latitude 
in color saturation, dependent chiefly upon the degree of overlap of 
the three primary elements. In other words, there is a color-satura- 
tion latitude, dependent upon the transmissions of the screen elements, 
as distinct from a true emulsion latitude. These can be to some ex- 
tent correlated and a compensation made. 

In photographing a subject in which there is ample color contrast 
and the colors are reasonably saturated, perfectly flat lighting can 
give an entirely satisfactory result. The color contrasts will provide 
brilliance. If the subject be illuminated by a number of lamps in 
various positions, so that a large range of light-intensity is included, 
color dilution can easily step in and affect local and even overall 
fidelity. If, on the other hand, the total range of light-intensity falling 
upon any given object in the set be kept within a range that can be 
computed from a wedge spectrogram in color of the color stock, then 
the color rendering of the brightest and least illuminated parts of the 
object will both be truly recorded. The apparatus used is an ordi- 
nary diffraction-grating spectrograph, with a neutral gray wedge hav- 
ing a density range of to 2.5 in front of the slot behind which the film 
is exposed. The light-intensity range of the wedge is thus 100 per 
cent at base line to 0.4 per cent at the top of the wedge. 

The "normal" exposure for the spectrogram has been taken as that 
giving a density of 1.0 in the most exposed portion, in standard devel- 
opment time in the Dufaycolor negative developer : 

Nov., 1937] 




Sodium Sulfite (dry) 
Sodium Thiosulfate 
Sodium Silicate 
Water to make 

Caustic Soda 
Water to make 

10 grams 
25 grams 
25 grams 
10 cc. 
1000 cc. 

10 grams 
1000 cc. 

Equal parts are mixed for use, and 3 minutes of development is given 

For testing Dufaycolor stock the film is exposed through the matrix 
or reseau, and developed as a negative, so that the wedge spectrogram 
appears in complementary colors. It is then also developed and re- 
versed, giving a natural-color 
spectrum. In a print from a 
normal negative, or in a reversal 
print, the peaks throughout the 
spectrum will appear of saturated 
color that is, as saturated as 
the reseau primaries will permit, 
degraded with black, as the 
wedge steepens ; while as one fol- 
lows any spectral band from the 
peak to the base, the color be- 
comes more and more pure that 
is, less degraded with black, and 
would in an ideal case still be 
pure at the base line, i. e., over 
the whole light range of the 
wedge, in this case 1:250. It 
will be found in general, how- 
ever, that the color becomes 
diluted and may even appear almost white before the point of 
maximum exposure has been reached on the base line. But it is 
not difficult to find by visual inspection the range at any particular 
spectral position over which the color appears undiluted, and by 
simply measuring this length and converting it into terms of light- 
intensity range, the limits of intensity can be ascertained. 

That the change in color at each end of the light-intensity range is 
not due to a gamma wavelength effect at the foot and shoulder of the 

FIG. 1. Characteristic curves of 
Dufaycolor motion picture negative 
film exposed through blue, green, and 
red filters, showing similarity in gen- 
eral shape. 



[J. S. M. P. E. 

characteristic curve may be seen from Fig. 1, where the Duf ay color 
negative material is shown exposed behind three standard trichro- 
matic filters. 

A simple experiment to show the failure of an additive photo- 
graphic material to retain color fidelity over too long a range of light- 
intensity was made by photographing colored cards three feet long 
and nine inches wide, illuminated by a 100-watt tungsten lamp placed 
four inches from one extreme side. The rate at which the light tailed 
off was measured by the inverse square law. Within the light-inten- 
sity range of approximately 12.5 to 1 the color remains accurate and 
is in good agreement with that obtained from the wedge spectrogram. 


FIG. 2. 

490 500 560 M>0 650 

Transmissions of reseau elements of normal Dufaycolor 
motion picture stock. 

This range is dependent to some extent upon the saturation of the 
reseau or matrix primaries. The standard material has transmissions 
as shown in Fig. 2. 

It was demonstrated by means of lantern-slides that full color satur- 
ation was maintained over a longer range of light-intensity in the case 
of a reseau composed of saturated colors, while the range was consid- 
erably shortened in the case of an experimental reseau made with 
very dilute primary colors. Color fidelity (as regards saturation) 
was thereby shown to depend, in an additive process, upon the "color 
latitude" given by the degree of saturation of the three elements, quite 
apart from the color characteristics. 

At this point in the presentation of the paper, a short piece of motion picture film 
was projected, showing a small studio set lighted by white flame arcs so arranged that 


the intensities of the light falling upon the two sides of the set, as measured by re- 
flection from the disk of a photometer, were identical; in other words, the range of in- 
tensity was 1:1. Another shot followed, in which the lamps were so arranged as to 
change the intensity to 5:1; and in a third shot to 25:1. 

The general satisfactoriness of all three shots indicates that color 
fidelity is unbalanced only when the light-intensity varies greatly at 
contiguous spots, such as the side and front of an artist's face lighted 
by oblique illumination or by too intense spotlighting. 

Many photographers complain that they are unable in natural- 
color photography to employ the hard lighting effects that they use 
for dramatic effect in black-and-white photography, owing to the loss 
of color caused at the high spots. But an experiment will show that 
in the case of oblique lighting, if the angle of the spotlights be less 
pronounced (that is, the spot illumination be more from the front 
than the side than in the case for black-and-white) , full color fidelity 
can be maintained and the artistic effect still obtained by color con- 

The producer will argue that if his main effects are achieved, a few 
local losses of color saturation are of no consequence, and in any case 
will not be appreciated by the audience. To a great extent that is 
correct; but after examining Dufaycolor films on projection over a 
number of years, the superiority of the results attained with definitely 
flatter lighting than is used in black-and-white photography can be 
vouched for; and, provided that the luminosity range lies (in the 
case of the reseau now in use) within about 12.5:1, the range indicated 
by visual examination of spectrograms, the results are of optimal 
overall color fidelity. 





Summary. The effect of uneven slit illumination upon the reproduction of vari- 
able-width sound-tracks of the unilateral and bilateral types are analyzed. The 
ground-noise reduction for unilateral tracks is considered, as accomplished by a 
single-vane shutter so that the modulations are recorded symmetrically with respect 
to the center of the track. For bilateral tracks both electrical biasing and double-vane 
shutters are considered for effecting ground-noise reduction. 

When the slit illumination increases linearly across the sound-track, bilateral 
records either with electrical or shutter ground-noise reduction are not distorted. 
When the illumination changes by 20 per cent across the sound-track by any uniform 
function that would correspond to any actual case of faulty adjustment, the harmonic 
distortion in no case exceeds 3 per cent for fully modulated signals. Further, the per- 
centage of distortion decreases with the signal strength. Thus, while the reproduction 
of variable-width recordings is subject to distortion by uneven slit illumination, it is 
not excessive on equipment properly serviced. 

In reproducing sound from either variable-density or variable- 
width records, faulty illumination of the sound-track can cause vol- 
ume attenuation and quality distortion. The nature of the distor- 
tion depends upon the nature of the faulty illumination, but the 
effect of uneven illumination of the reproducing slit is of special in- 
terest. This is because variable-density records are not distorted, 
and the distortion of variable-width records is a function of the il- 
lumination and the type of variable-width track being reproduced. 

This paper considers the effect upon the quality of sound repro- 
duced from unilateral tracks with the anti-ground-noise (A. G. N.) 
accomplished by a single-vane shutter, bilateral tracks with electri- 
cal bias A. G. N., and bilateral tracks with double- vane shutter A. G. N., 
all as a function of the non-uniformity of illumination of the repro- 
ducing slit. A harmonic analysis is given for three distinct types of 
non-uniform illumination, and by combining these three types it is 
possible to approximate most conditions met in actual reproduction. 

* Received June 25, 1937. 
** RCA Manufacturing Co., Hollywood, Calif. 






i.l.*-b-+ ISL 

i L** z T h 



i Energy fellmy on Photocell 

f//yM/llumir><rf/i/nKt:. TJi/s /J 

"t-.^T^t ^ of Ia+> 

FIG. 1. Unilateral track with shutter. 


FIG . 2 . B ilateral track with electrical bias . 

jz 3- +cj/'rnut. 



O 10 ZO 30 4O SO 6O 70 6O 9O 

FIG. 3. Bilateral track with shutter. 



In Figs. 1 to 9 the transmitting areas of three types of sound-tracks 
are represented by the shaded portions. The signal is of constant 
frequency u/2ir and the amplitude C is arbitrary and can vary from 
C = to C = h/2 for a unilateral track and C = h/4 for bilateral 
tracks, h is the maximum width of the sound-track. The clearance 
d, for A. G. N. R., is illustrated for each type of track, d is treated as 
a variable, but only in the case of electrical bias does it influence 
quality more than to change the amount of ground-noise. The 
width of the light-beam illuminating the track is k, and we shall 
consider only the case in which the slit width is sufficiently small as 
not to introduce harmonic distortion. 

In Figs. 1 to 10 are illustrated the intensity / of three types of slit 
illumination across the total sound-track. The equation of the edge 
of the sound-track and the equation of the intensity of the illumina- 
tion are shown in each figure. It will be noted that for each figure 
the track and slit illumination are represented by the same coordi- 
nate system, but the coordinates are not the same for all the figures. 
This is done to facilitate the mathematical calculations. 

The radiant energy F transmitted by the film is indicated by an 
integral of the form 

E = f I k dy (1) 

where / is the intensity of illumination of the film at any ordinate 
y; k is the constant width of the reproducing light-beam; and dy is 
the distance from y to y + dy. The limits of the integral are set by 
the boundaries of the sound-track. The symmetry of bilateral 
tracks makes it necessary to integrate only over one track. In Figs. 
5, 6, 8, and 9 the distortion of both tracks obviously add. In Figs. 
2 and 3 the integration has not been carried out because symmetry 
considerations make it obvious that the distortion of one track will be 
completely counteracted by the other. 

Only modulated energy, E^, is reproduced from the photocell, 
and therefore in substituting the integration limits the constant 
terms due to track clearance have been omitted. It will be noted 
that the results expressed as E mod represent a complete Fourier analysis 
of the modulated signal reproduced. Naturally the result will be 
exactly the same if, instead of regarding- the slit- width as con- 
stant and the illumination as non-uniform, as we have done, the 



Only V* Harmonic. Distortion 

PkKCtNTMC Ib of L>*Ib 

FIG. 4. Unilateral track with shutter. 

Ihedtoninceij'ifltrnduces a second harmonic, bulpnxtica/lyifcanbtneyleiied so : 

I a 

! z % 


OnKj Z*& k It Harmonics 

<! is r.., 1 . *' I 

PBBCEMTk&t Ib of I + Ib 

FIG. 5. Bilateral track with electrical bias. 



Reproducer 3/tf ' I//t/m /nation 


Onlvj 2"-^ A. 3* Harmonics 

FIG. 6. Bilateral track with shutter. 



FIG. 7. Unilateral track with shutter. 


illumination over the slit can be regarded as constant and the width 
of the slit as changing according to the equation for / given each figure. 
Relative to this last concept, it might be well to emphasize that we 
have implied throughout that the slit-width was always sufficiently 
small as not to introduce any harmonic distortion. 

In Figs. 1 to 9 are shown graphically the percentage harmonic dis- 
tortion for fully modulated signals as a function of the non-uniformity 
of the recording slit illumination. It will be noted from the equa- 
tions for E mod that the harmonic distortion decreases for small modu- 
lations. For parabolic non-uniformity the distortion is approxi- 
mately proportional to the square of the amplitude of the signal. 
This has been illustrated graphically in the figures by showing the 
distortion for 50 per cent modulation. Thus the graphs represent 
the distortion introduced by faulty slit illumination in the most un- 
favorable light. 

In addition to varying the non-uniformity of slit illumination ac- 
cording to the three general types shown in Figs. 1 to 9, the distortion 
of other types can be computed by considering the addition of two 
types as is illustrated in Fig. 10. In computing the distortion due to 
two of the general types it is necessary to add the distortions alge- 
braically, for usually the distortions compensate one another. 


(1} Slit illumination in a reproducer that increases perfectly uni- 
formly across the slit produces 2nd-harmonic distortions in a unilat- 
eral track. The percentage of distortion is almost proportional to the 
signal strength and the variation in intensity across the slit. 

(2} Bilateral tracks with electrical bias or shutter bias are not in- 
fluenced by a perfectly uniform change in illumination over the en- 
tire sound-track. 

(3) With non-uniform slit illumination that is either greatest or 
least at the center, unilateral tracks produce only 3rd harmonics. 
For the same illumination, bilateral tracks produce a 2nd harmonic 
and a slight 3rd harmonic. 

(4) The more unsymmetrical the non-uniformity of illumination 
about the middle of the slit, the more bilateral tracks are favored 
ver a unilateral track. This is illustrated by Fig. 10. 

(5) The amount of distortion produced by any type of non-uni- 
formity of illumination is almost directly proportional to the amount 
of non-uniformity. 





FIG. 8. Bilateral track with electrical bias. 

of la Ib . 

FIG. 9. Bilateral track with shutter. 

Nov., 1937] 



The effects of three distinct types of non-uniform slit illumination 
upon the reproduction of three types of variable-width sound-track 
are treated by harmonic analysis. The nature and amount of dis- 
tortion produced are functions of the type and amount of non-uni- 
form slit illumination, the type of sound-track, and the signal strength. 


FIG. 10. Method of computing distortion for 
tracks other than those shown in Figs. 1 to 9. 

Although non-uniform slit illumination in general distorts the repro- 
duction of variable-width sound-track, the amount of distortion 
is usually less than 1 per cent; thus, by properly servicing a repro- 
ducer, the amount of distortion due to non-uniform slit illumination 
can be made negligible for reproducing all types of variable-width 
sound records. 





Summary. The details of the organization of the Research Council of the 
Academy of Motion Picture Arts and Sciences are outlined, and brief sketches are 
presented of the work of several of the more important Committees working under the 
auspices of the Council, including the Committee on Improvement of Release Print 
Quality, the Silent Camera Committee, Committee on Screen Illumination, Com- 
mittee on Industrial Education, the Scientific Committee, and the Sound Recording 

Although many industries have supported organizations devoted to 
cooperative research and development, each of which has been molded 
to fit the particular requirements and demands of that particular in- 
dustry, we of the motion picture producing industry in Hollywood 
believe that in the Research Council of the Academy of Motion Pic- 
ture Arts and Sciences we have an organization that is both unique 
and unusual. 

Many of you are probably more familiar with the organizations in 
other industries than I am, such as the American Petroleum Institute, 
the National Electric Light Association, the National Automobile 
Chamber of Commerce and many others, all of which conduct tech- 
nical organizations of one sort or another as part of their activities. 

Although the Academy of Motion Picture Arts and Sciences has 
engaged in some cooperative research ever since its organization in 
1927, the Research Council as it now functions was organized in 1934, 
and its first chairman after the reorganization was S. J. Briskin, Ex- 
ecutive Vice-President of RKO-Radio Studios. The operation of the 
Research Council is patterned after the technical organizations of the 
various trade associations, as their methods could be applied to the 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received May 
21, 1937. 

** Chairman, Research Council, Academy of Motion Picture Arts and Sciences; 
General Manager, Metro-Goldwyn-Mayer Studio, Culver City, California. 


motion picture industry, for the sole purpose of giving to the produc- 
ing companies here in Hollywood, and their affiliates throughout the 
world, the benefit of the fullest cooperation of all the technicians en- 
gaged in the production and exhibition of motion pictures, to eliminate, 
wherever possible, duplication of effort and expense. 

As an organization of technical men you are most interested in the 
details of the work of our many Committees. The Council is com- 
posed of one representative from each of the producing companies 
participating in the program, and acts as a Board of Governors ad- 
vising on and directing the work of the Committees. 

In 1934 the Research Council had eight cooperative projects in the 
hands of eight separate committees enlisting the interest of approxi- 
mately seventy-one technicians. Its activities have grown until at 
the present time it has thirty-six committees with approximately one 
hundred and eighty different company representatives working on 
these committees. During the past year we had more than two hun- 
dred and fifty committee meetings, averaging approximately five a 

To acquaint you with all the details of our work would take days, 
but I will attempt to give you in the next few moments a brief sketch 
of the work of several of our Committees. Of major importance at 
the moment is the Committee on Standardization of Theater Sound 
Projection Equipment Characteristics, which, under the Chairman- 
ship of John Hilliard of Metro-Goldwyn-Mayer Studios, has recently 
recommended a Standard Electrical Characteristic that should 
greatly improve the quality of sound in all theaters. 

A Committee on Improvement of Release Print Quality, under the 
Chairmanship of L. E. Clark of the Dunning Process Company, has 
for many months past been investigating every possible method that 
might be adapted to an eventual standard density. As we all know, 
there is very little actual coordination among the few laboratories 
here in Hollywood processing negative film and the many laboratories 
throughout the world making release prints. The last report of this 
Committee indicates that it has finally solved the problem, and within 
the next few months the industry will have a simple and effective 
method of comparing print densities to a standard calibrated density- 
measuring device that we "plan to build and install here in Hollywood 
as a service to the entire industry. 

The Silent Camera Committee, under the Chairmanship of Virgil 
Miller, has been at the service of the camera manufacturers and the 

486 W. KOENIG LT. S. M. P. E. 

producers for the purpose of testing newly developed, so-called silent 
cameras, and for assisting in the development and testing of various 
blimp- and camera-silencing devices. In connection with its work 
the Committee has recently drawn up a set of camera noise testing 
conditions which we plan to make available to the industry so that 
the results of camera tests according to this standard procedure and 
under these standard conditions anywhere in the world will compare 
directly with the results of tests made here in Hollywood. 

The Screen Illumination Committee, under the Chairmanship of 
John Aalberg of RKO-Radio Studios, although originally set up to 
consider illumination conditions in studio viewing rooms only, some 
months ago expanded the field of its activities and is now working on 
plans for a national survey to determine actual illumination condi- 
tions in the theater field and to give the release printing laboratories 
accurate and definite data as to the screen illumination in the theaters. 

As a result of a number of complaints sent to us by the producing 
companies regarding arc light noise, which has proved troublesome to 
the studio recording departments, we have recently organized a Com- 
mittee under the Chairmanship of Thomas Moulton of United Artists 
Studios, to investigate the problem for the purpose of determining the 
causes of the trouble and suggesting remedies for it. 

In addition to these purely technical projects dealing with motion 
picture production and exhibition to which we have previously con- 
fined ourselves, we have this last year ventured into an entirely new 
field i. e., that of industrial education. As a first step in this ac- 
tivity, the Committee on Industrial Education arranged a prelimi- 
nary course in sound recording with A.P. Hill of Electrical Research 
Products, Inc., as instructor. 

The first course, given in the Spring of 1936, met with such tre- 
mendous success in the studios that upon the unanimous request of 
the studio sound department heads and a large number of techni- 
cians whom we could not accommodate in that course, we repeated 
it again this fall. 

In addition to this preliminary course, a more comprehensive ad- 
vanced course dealing with theory and operation of sound equip- 
ment was given this fall, meeting twice a week for twenty-four weeks 
at the Hollywood High School. 

The services of the four instructors who handled this advanced 
course were made available to the Council through the cooperation 
of their employing companies. The instructors, all of whom have 


given a great deal of time and effort to putting the course over are 
L. E. Clark, John Milliard, Fred Albin of United Artists Studios, 
and Harry Kimball of Metro-Goldwyn-Mayer. 

We have trained in the courses a total of two hundred and thirty- 
five studio sound department employees, all of whom will be of much 
greater value to their employing companies this year than they were 
last because of having undertaken the study. In setting up these 
courses it was specified that enrollment would be limited strictly to 
employees of the studios who are already engaged in sound record- 
ing, inasmuch as it was not our purpose to complicate the employ- 
ment situation by teaching men who were not already engaged in 
this work. 

The field of internal industrial education is, of course, unlimited, 
and there are a great variety of subjects that might be discussed by 
groups within the studios to the ultimate great advantage of their 
companies, and we contemplate expanding this part of our work as 
rapidly as our facilities and finances will permit. 

The Committee on Industrial Education, under the Chairmanship 
of Dr. J. G. Frayne of Electrical Research Products, Inc., assisted 
by Barton Kreuzer of the RCA Manufacturing Co, Dr. Burton F. 
Miller of Warner Brothers Studio, William Thayer of Paramount 
Studio, and Ralph Townsend of 20th Century-Fox Studio, is now 
discussing additional plans for a very general course in sound record- 
ing for film editors, a course in the latest developments of acoustics 
for sound technicians, several laboratory subjects, new developments 
in electrical testing, new developments in the re-recording and re- 
production of music and other subjects. 

In the Scientific Committee, under the Chairmanship of Carl 
Dreher, the producing companies have available a group of highly 
trained technicians who as a body are keeping themselves fully 
informed, from the standpoint of the producing studios, of every 
development in television. The producers look upon this Committee 
as a highly qualified group of "watch dogs" who are following tele- 
vision s every move. 

Our Sound Recording Committee, under the Chairmanship of 
E. H. Hansen of 20th Century-Fox Studio, consisting of the heads 
of the major sound departments, is concerned with group improve- 
ments in studio recording practices. At the present time this Com- 
mittee is conducting five or six separate projects, one of which is 
of particular interest to me as a producer. As you all know, sound 

488 W. KOENIG 

as heard in the theater is quite different from the original sound re- 
corded upon the set. The addition of sound effects, background 
music, off-stage dialog, etc., sometimes completely changes the com- 
plexion of a scene. 

Recognizing the importance of the dubbing operation to a fin- 
ished picture, the Sound Recording Committee recently decided to 
conduct an interesting experiment. The dialog, background music, 
and sound effects tracks of one reel of a completed production are 
now being sent through the dubbing operation in each of our eight 
studios. When finished, we shall have eight different versions of 
the same reel, all dubbed from the same original tracks and I ven- 
ture to say that eight very different finished versions will come out 
of this experiment. 

I hope that the Sound Directors will not confine this reel to them- 
selves but will show it to every sound technician in all the studios, 
in order that each will get the benefit of the comparison between the 
work of the other studios' dubbing departments. 

In closing I might say that the Research Council is steadily build- 
ing up a background of achievement that has not as yet been marred 
by a single failure. 

F. G. ALBIN** 

Summary. A new design of volume indicator for use in sound recording is de- 
scribed, embracing the features of peak amplitude response and a linear decibel scale. 
The peak response characteristic results in a better indication of peak amplitudes, 
and thereby affords protection of the modulator against overloads. The linear decibel 
scale extends the useful range of the indicator about 12 db. , thereby indicating low levels 
formerly imperceptible. 

The volume indicator is the chief tool of the sound recording mixer 
in gauging his recording level, which must be maintained consistently 
within limits for several reasons. First, the range must be com- 
pressed so that a satisfactory signal-to-noise ratio is always main- 
tained, even at the lowest recording level. Furthermore, since 
there is a definite limit to the amplitude that can be accommodated 
by the modulator, the level must never be so high as to allow the peak 
amplitudes to overload the modulator. 

The nature of recorded sound is wide and varied. The wave-forms 
are most frequently very complex, with peak factors often in excess 
of 15. Furthermore, the waves are transient, and may persist only 
for relatively short periods. For safeguarding the modulator against 
overloads, and since the modulator follows the wave-form, the vol- 
ume indicator should respond to the peak amplitudes, and the period 
of response should be shorter than the period of duration of the tran- 
sient wave. Fortunately, however, there is a lag in the response of 
both the ear and the eye, and overmodulation may be permitted for 
short intervals without serious degradation of fidelity if the interval 
is so short as not to be observed on the indicator. Therefore, the re- 
quired speed of response of the volume indicator is somewhat reduced. 

Because of the transient nature of the recorded sound, the indicat- 
ing meter should be highly damped, so as not to overshoot the ulti- 

* Presented at the Spring, 1937, Meeting at Hollywood, Calif. ; received May 
18, 1937. 

** United Artists Studio Corp., Hollywood, Calif. 




[J. S. M. P. E. 

mate reading. A slow return from the indicated reading is allowable 
and, in fact, preferred, since it allows the mixer time in which to reg- 
ister the indication. 


FIG. 1. (.4) Linear amplitude scale; (B) linear decibel scale. 

Level Range. The uncompressed range of sound level en- 
countered in recording covers approximately 80 db. Modern record- 
ing latitude does not exceed 50 and, in general, is limited to about 30 
db. The usual volume indicator has a range of 12 db. for the upper 
85 per cent of its scale. Allowing the upper 6 db. of the scale for 
exceptionally high levels establishes the maximum normal level, or 
100 per cent modulation, at midscale. The first 15 per cent deflec- 
tion will be disregarded because of the considerable non-linearity in 
that region and the inaccuracy of readings. The 15 per cent low limit 
will be arbitrarily chosen to apply to both types of meters while com- 
paring them. 

FIG. 2. Circuit of linear-decibel volume indicator. 

The remainder of the 85 per cent or 30 per cent of the scale is left 
for the 6-db. useful range of the meter. Any level lower than 6 db. 
below overload, or less than 50 per cent modulation, causes less than 
15 per cent scale deflection, leaving only 6 db. as the useful range of 
the meter. For that reason, background sounds, such as music, or 

Nov., 1937] 



low-level speech, such as whispers, are practically imperceptible on 
the indicator, and the monitor must be relied upon for judging the 
level. The recent extension of the recording range aggravates the 
condition, and the volume indicator is wholly inadequate to indicate 
levels over the range recorded. In practice, full-scale deflection is 
often used for 100 per cent modulation, thereby sacrificing the indi- 
cations above the overload point and extending the useful range by 
approximately 6 db. 

Linear Decibel Scale. A linear decibel scale is shown in 
Fig. 1. Here, as with the former scale, the full deflection is 6 db. 
above 100 per cent modulation, or 200 per cent. However, 100 per 
cent modulation occurs approximately at 85 per cent of full scale, 
leaving about 70 per cent of the scale for the useful range. Fur- 
thermore, 15 per cent of the scale 
represents 18 db. below 100 per 
cent modulation. The useful 
range is 18 db., which is 12 db. 
greater, or 4 times the amplitude 
of the former. Also, 70 per cent 
of the scale is useful, as compared 
with 30 per cent of the former. 

The ear recognizes equal 
changes of level as equal incre- 
ments of sensation; in other 
words, it has a logarithmic re- 
sponse to change of level. The 
volume indicator should respond 

likewise; equal increments of sound level should cause equal incre- 
ments of volume indicator deflection. Therefore, the deflection of 
the volume indicator should be proportional to the input level in 

Fig. 2 is the circuit diagram of the linear decibel peak reading vol- 
ume indicator, employing a standard volume indicator meter. Es- 
sentially, the circuit consists of a stage of amplification, a full-wave 
vacuum tube rectifier, and a d-c. amplifier having an exponential re- 
sponse to input. The first amplifier has a main gain control calibrated 
in decibels and a vernier control for compensating for tube amplifica- 
tion variations. Other vernier adjustments, not shown, correct for 
other tube variations, and certain other refinements are omitted 

FIG. 3. Linear decibel scale. 

492 F. G. ALBIN 

from the drawing. The diode rectifier may be enclosed in the en- 
velope with the amplifier. 

The d-c. amplifier employs a tube having three grids. The first 
grid is connected to the plate through a resistance. The second grid 
is used as a space-charge grid, and the third as the control grid. A 
bridge circuit in the anode circuits is so adjusted that the normal 
meter current is zero. The input signal applies a negative potential 
to the control electrode and lowers the plate current. According 
to the behavior of the usual multiple-electrode tube, the current in 
the second grid increases with decrease of plate current. Both these 
changes contribute to unbalancing the bridge and causing current 
to flow through the meter. 

It is beyond the scope of this paper to describe in detail the action 
that causes the exponential response. Briefly, however, it is due to 
connecting the first grid to the plate. As the plate current decreases, 
the potential increases, and thus the first grid voltage and the current 
both increase. The combined plate and first grid current decrease, 
however, and in a manner that is proportional to the logarithm of the 
control grid voltage change over a limited range. 

Excessive input voltage merely reduces the plate current to zero, 
beyond which there is no further change of tube or meter currents, and 
no damage to the tube or meter is possible. The meter is standard 
in every respect except for the linear decibel scale (Fig. 3). The 
bridge circuit, which balances out the zero signal anode currents, has 
the additional merit also of restoring the meter current to zero in the 
event that the cathode current of the tube is stopped. A further 
feature is that variations of B voltage are balanced out of the meter 
circuit to a large degree. 

A choice of tubes is necessary for best performance. With se- 
lected tubes, the response is linear for at least 24 db. Establishing 
0.5 db. as the tolerance over the 24-db. range, the proportion of good 
to rejected tubes obtained on the open market was one to three. 
Extensive tests of the apparatus have proved it to be practicable and 
popular as a volume indicator for recording. 


M. J. DI TORO** 

Summary. In the reproduction of a hill-and-dale recording, the curve traced by 
the reproducer stylus differs from the recorded curve, with (he consequent introduction of 
both frequency and amplitude distortion. This distortion is here catted "tracing dis- 
tortion," and must be tolerated only in virtue of the physical necessity of a finite tip 
radius for the reproducer stylus. A description is given of the results obtained in a 
study of this phenomenon, together with curves and formulas for the quantitative deter- 
mination of the magnitude of both the amplitude distortion (i. e., harmonic generation) 
and the frequency distortion (i. e., decay in fundamental), as functions of the amplitude 
and frequency of the recorded undulation, the linear groove speed, and the tip radius 
of the reproducer stylus. 

A mong other conclusions reached, it is shown that the maintenance of the minimum 
radius of curvature of the recorded undulations at least equal to or larger than the tip 
radius of the reproducer stylus is an extremely inaccurate criterion of good-quality 
reproduction. For "constant-velocity" recordings, less than 10 per cent rms. har- 
monic generation is obtained when the minimum radius of curvature of the recorded 
undulation is greater than 5 times the tip radius of the reproducer stylus. Moreover, 
the generation of harmonics due to tracing distortion is a much more serious limitation 
upon the quality of the reproduction than is the loss or attenuation of fundamental 
frequency, as, for example, in cases where the loss of fundamental is only 2 db., the 
harmonic generation is prohibitively high, being much greater than 10 per cent. 

The Introduction and Section I give a physical account of the phenomenon of trac- 
ing distortion and deal with all the data necessary for a practical application of the 
formulas derived in Section II. 


An electrical phonograph system consists essentially of a record- 
driving mechanism, a reproducer, an amplifier, and a loud speaker. 
Each of these component devices of the system is capable of produc- 
ing distortion of some kind, which will render the reproduced sounds 
an improper mechanical-acoustical conversion of the undulations re- 
corded on the record. Most of this distortion may be classified as 
being one or both of two general types. One type is known as fre- 

* Presented at the Fall, 1937, Meeting at New York, N. Y.; received Sept. 1. 

** Thomas A. Edison, Inc., West Orange, N. J. 


494 M. J. Di TORO [J. S. M. P. E. 

quency distortion, and arises from attenuation or magnification of 
certain portions of the frequency spectrum passing through the phono- 
graph system. The other type is known as amplitude distortion, in 
which the magnitude of the reproduced sound is not proportional to 
the magnitude of the recorded undulation. From an analysis of am- 
plitude distortion, it is known 1 that when the wave-shape of the re- 
corded undulation is sinusoidal, the distorted reproduced sound con- 
sists of a fundamental component of the same frequency as the re- 
corded undulation, plus harmonic components that do not exist in the 
recorded undulation. 

Inasmuch as amplifiers and loud speakers are used to a considerable 
extent in many forms of sound systems, their characteristics with re- 
spect to distortion have been studied in great detail, so that it is now 
possible to design devices of this type in which the distortion is at 
such a low level as to be negligible. Distortion arising from speed 
variation (flutter) in the record-driving mechanism has been mate- 
rially reduced by ingenious designs of speed-governing systems. 2 ' 3 A 
considerable amount of study has also been given to phonograph 
reproducers 4 ' 5 to eliminate both frequency and amplitude distortion. 
In well designed reproducers the mechanical transducing system can 
usually be made such that both these forms of distortion are again 

A remaining form of distortion in the phonograph system is, how- 
ever, present in the phonograph reproducer. This distortion does 
not arise in the mechanical system of the reproducer itself, but occurs 
because of the finite radius of the reproducer stylus that is required 
to avoid excessive wearing of the record. When the tip dimension of 
the reproducer stylus becomes comparable with the wavelength of 
the undulations in a phonograph record, the stylus will not follow a 
path of exactly the same wave-shape as that followed by the sharp 
cutting stylus of the recorder used in making the record. An extreme 
case occurs when the radius of curvature of the recorded undulation 
becomes smaller than the tip radius (of curvature) of the reproducer 
stylus. For this condition, it is quite obvious that the reproducer 
stylus can not follow precisely the recorded undulation. In the past 
literature on this subject many authors 6 ' 7 have regarded this to be a 
limiting condition for phonographic reproduction, and have attempted 
to design the system so that the minimum radius of curvature of the 
recorded undulation would always remain at least as large as the radius 
of curvature of the reproducer stylus. However, even when this 

Nov., 1937] 



condition is met, those who are familiar with phonograph practice 
recognize certain deficiencies in the reproduction of phonograph rec- 
ords. For instance, on long-playing disk records in which the outer 
groove has several times the length and therefore several times the 
linear velocity of the inner groove, a loss at high frequencies and a 
raucous quality have been noted in the reproduction from the inner 
grooves. It has been noted that this change is less marked when the 
amplitude of the recorded undulation is reduced. Some engineers, 

FIG. 1. Tracing distortion: (1) recorded un- 
dulation; (2) parallel cu